DIE ERDE 139 2008 (1-2) Special Issue: Fog Research pp. 11-44

• History of Science – Hydrometeors – Fog – Rain – Dew

Detlev Möller (Cottbus)

On the History of the Scientific Exploration of Fog, Dew, Rain and Other Atmospheric Water Zur Geschichte der wissenschaftlichen Erforschung von Nebel, Tau, Regen und anderem Atmosphärenwasser

With 5 Figures and 3 Tables

Atmospheric water, today classified as hydrometeors (fog, cloud, precipitation) and depositions (dew, frost etc.), has fascinated people since ancient times as ‘heavenly’ phenomena that were early recognised to be part of the water cycle. However, these phenomena were not described in detail before a first understanding of fundamental atmospheric physics and of the basic chemical composition of the air had been acquired. This contribution will start with a short introduction of the ancient philosophic view of the atmosphere and then proceed to several early modern ap- proaches to understand water evaporation and droplet formation and to a first scientific descrip- tion of the phenomena of dew, cloud and rain. Here, for the first time in modern scientific literature, the early approaches to chemical-meteoric water analysis are presented.

1. Introduction to these “waters”, before Wells (1814) ascer- tained that dew did not result from water drops 1.1 The forms of atmospheric which fell out of the sky. The phenomena – fog, water (terminology) mist and clouds, precipitation (rain, snow, hail) and dew – have been described since Antiquity. Atmospheric water includes physical water in all A phenomenological understanding of the phys- aggregate states, i.e. gaseous, liquid (in droplet ical (but not chemical) processes associated with form) and solid (ice particles). The historic term hydrometeors was complete only by the end of ‘atmospheric waters’ is ‘hydrometeors’ in cur- the 19th century. Today the physics and the rent terminology, i.e. meteoric water. For histor- chemistry in the aerosol-cloud-precipitation ic reasons, dew had been considered to belong chain are relatively well understood – also with 12 Detlev Möller DIE ERDE relation to climate. However, it seems that be- from Greek (= vapour) and cause of the huge complexity a mathematical (= sphere), was not regularly used before the be- description of the processes (i.e. the parame- ginning of the 19th century. Willebrord Snelius, terisation of the chemistry and also for climate also called Willebrord van Roijen Snell (1580- modeling) is still under construction. 1626), a Dutch astronomer and mathematician, translated the term “damphooghde” (in German Clouds and precipitation are not only the atmos- “Dunsthöhe” or “Dunstkugel”) into Latin pheric link in the global water cycle but also an “atmosphaera” in 1608; Guericke used “aerea important reservoir for chemical processing and sphaera” (Lufthülle). In old German publications the transportation of tracer substances. To be the term “Dunstkreis” also was used instead of sure, clouds are distant from the earth’s surface “Atmosphäre”; in addition, in the 19th century the (with the exception of fog!) and thus not simple term “air ocean” (Luftmeer, Luftozean) was also to study – even nowadays. Precipitation (rain, used, in analogy to the sea. snow and hail), in contrast, has always been eas- ier to observe by human sensors (through see- In ancient times atmospheric (weather) observa- ing, feeling, smelling and tasting) and to collect tions were closely associated with astronomy, for volume estimation and analysis. Precipitation and everything above the Earth’s surface was was probably long considered a climatic precon- named ‘heaven’ or ‘aether’. Already before the dition for survival by early humans, but also – year 600 BC, the Greek word ‘metéron’ (or with its extreme events – as catastrophic, for ‘metéora’) was already in use. It means “a thing housing as well as for farming. In addition, the in the air”. Until the end of the 18th century, mixing of air and water with pollutants (accu- (meteors) denoted all celestial phenom- rately related to as “foreign bodies” in the old ena, aqueous, vaporous, solid and light. terminology) has been known since Aristotle; the role of precipitation in cleaning the envi- The word ‘air’ is derived from Greek and Latin ronment is wonderfully described by Evelyn aer. It is not known what the root of the German (1661: 20): “It is this horrid Smoake which ob- word “Luft” is (the term Lufft was already used in scures our Churches and makes our Palaces the Middle Ages); Möller (2006) discusses the look old, which fouls our Clothes and corrupts possible relation with “Licht” (light). the Waters, so as the very Rain, and refresh- ing Dew which fall in the several Seasons, pre- The gaseous substances, which were observed cipitate this impure vapour, which, with its in alchemical experiments, were named fumes black and tenacious quality, spots and con- (“Dünste”), vapours (“Dämpfe”) and airs taminates whatever is exposed to it”. (“Lüfte”); atmospheric air (called common air) was still regarded as a uniform chemical body. Atmospheric waters were first studied alchemi- The meaning of different terms in different lan- cally, by rain water distillation in the 17th century guages (e.g. French, English and German) has (see section 5). But systematic studies of de- been changing over time; the words were used position (precipitation chemistry) only began in a slightly different sense by various natural- with Liebig’s discovery that plants assimilate ists. For example, German Dunst (plural Dünste) (chemically fixed) nitrogen dissolved in rain. was first used in the sense of exhalations (in modern term: emissions) and later as a synonym Humans dealt with and were fascinated by the for vapour – to be more exact: for visible vapour, properties of our atmosphere already in the an- i.e. very small water droplets, now named haze tique era. The term atmosphere, however, derived (a word which was not used before the 19th cen- 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 13 tury). In English, the term steam is used (only) trology. The idea that the motion of the stars and for water at boiling temperature diffusing in the planets influenced all processes on Earth and in atmosphere; in French and German there is no the atmosphere inhibited any progress of natu- equivalent term, only in a combination like “water ral sciences. Only in the orient Aristotle’s doc- vapour” (see Crosland 1962 for details). trine remained vital and first came to Europe in the 12th century, probably via Sicily where fa- Nowadays the terms air and atmosphere are mous alchemistic laboratories were established. widely used as synonyms. English dictionaries define atmosphere as “the mixture of gases sur- Between the great times of the Greek philoso- rounding the Earth and other planets” or “the phers who recognised the atmosphere only by whole mass of an aeriform fluid surrounding the visual observations and reflection, generalising Earth”. From a chemical point of view it is possi- it in philosophic terms, and the first instrumental ble to say that air is the substrate with which observations, there is a gap of almost 1500 years. the atmosphere is filled, in analogy to the hydro- Agricultural aspects and the understanding of sphere where water is the substrate or sub- plant growth (i.e., the beginning of commercial stance. Furthermore, air is an atmospheric sus- interests) initiated chemical research in the 17th pension containing different gaseous, liquid century. Chemistry, first established as a scien- (water droplets) and solid (dust particles) sub- tific discipline at around 1650 by Robert Boyle stances. Thus “air chemistry” is a more adequate (1627-1691), had been a non-scientific discipline term than “atmospheric chemistry”. (alchemy) by then. Alchemy never employed a systematic approach and because of its “secrets” no public communication existed which would 1.2 The atmosphere in research history have been essential for scientific progress. In contrast, physics, established as a scientific dis- In ancient times, the motivation to observe the cipline a long time ago, made progress, especial- atmosphere was clearly the driving force which ly with regard to mechanics, thanks to the im- increased the understanding of Nature. Thus, proved manufacturing of instruments in the 16th the first to describe a number of weather phe- century. Astronomers, observing the object of nomena and the water cycle was Aristotle in his their discipline through the atmosphere, also “Meteorologica”. Roman Emperors were not in- began to discover the Earth’s atmosphere. There terested in the continuation of Greek doctrines, are two personalities to whom deep respect must they, however, kept them. After the end of An- be addressed for initiating the scientific revolu- tiquity, around the 5th century, the occident for- tion in both the physical and chemical under- got the ancient scientific heritage and replaced standing of atmospheric water: Isaac Newton it by one single doctrine, the bible. Especially in (1643-1727), who founded the principles of clas- the Middle Ages, when religious belief prevailed sical mechanics in his ‘Philosophiae Naturalis with the view that all “heavenly” things were Principia Mathematica’ (1687), and, one hundred governed by God (which, after all, was the be- years later, Antoine-Laurent de Lavoisier (1743- lief of peoples all over the world and which led 1794), with his revolutionary treatment of chem- to the idea of the creation of the existence of istry (1789) which made it possible to develop special gods for many atmospheric phenomena), tools to analyse matter; this is why he is called probably monks were the first to observe the “the father of modern chemistry”. weather and take records, only by personal in- terest though. In those days any meteorologi- With the Age of Enlightenment in the 18th century cal (i.e., weather) observation was linked to as- the interest in natural processes generally expand- 14 Detlev Möller DIE ERDE ed. Travellers and biologists were interested in pollution) of their era. We also hold deep respect describing the climate and its relation to culture for our scientific ancestors for their brilliant con- and biota, and in the late 1700s chemists began clusions, based on scientific experiments with to understand the transformation between solid, very simple techniques and limited quantitative liquid and gaseous matter. A fundamental inter- measurements (to readers interested in more de- est in biological processes, such as plant growth, tails of these aspects I suggest Middleton 1965, nutrition, animal breathing among others, stim- Schneider-Carius 1955 and Gilbert 1907). With ulated the study of the water cycle, the gas ex- respect to the chemistry of hydrometeors (or in change between plant and air (including the find- general to air chemistry), however, a historical ing of fixed air, CO2, by Joseph Black in 1754), overview is still missing in the literature. the mineral input from the air by Liebig (1843), and a first understanding of matter cycles by early agricultural chemists (e.g. Knop 1868). With 2. Water and Air as Elements: from Antiquity the vehement industrial development in the mid- to the Middle Ages and Early Modern Times dle of the 19th century, air pollution as a new at- mospheric aspect became the object of interest 2.1 Ancient concepts of the elements of researchers; more exactly, air pollutant im- pacts (forest decline, human health, corrosion) Before the 6th century BC air was identified as were the first foci of research. Already in the late emptiness. Greek natural philosophers assigned 19th century, some impacts could be related to air and water to the four elements (materia pri- individual air pollutants (cause-receptor relation- ma: primary matter). Thales of Milet (624-546 ship, e.g. Stöckhardt 1871). The techniques to BC) was the first who tried to answer the ques- measure trace species, however, were still very tion of how the universe could possibly be con- limited. In spite of the fact that quantitative rela- ceived as made not simply “by gods and dae- tionships were missing, legislative acts concern- mons”. He defined water as a primary matter ing air pollution were passed in the 19th century. and regarded the Earth as a disc within the end- Nevertheless, air pollution remained a local prob- less sea. Pythagoras (about 540-500 BC) was lem until the 1960s. Then, with acid rain (despite probably the first to suggest the Earth be a the fact that it had already been described in sphere, but without explanation (only based on England in 1852 by Smith) the first regional en- aesthetic considerations). Parmenides of Elea vironmental problem appeared in Europe. And it (about 540-480 BC), however, explained the was only in the 1980s that global problems were spheroid Earth due to his observations of ships recognised in relation with climate change due floating on the sea; he was a scholar of Xeno- to the global change of the air’s chemical com- phanes from Kolophon (about 570-480 BC), the position. Localised catastrophic environmental founder of eleatic philosophy. Xenophanes events like the smog events in Los Angeles again was a scholar of Anaximander from Mi- (1944) and London (1952) helped to initiate at- let (about 611-546 BC). With Anaximander, a mospheric chemistry as a new discipline since scholar of Thales, and Anaximenes (from Mi- the beginning of the 1950s. let, about 585-528 BC), the cycle of pre-Socratic philosophers is closed. Anaximenes assumed – We can learn from history that all kinds of per- in contrast to Thales – air to be a primary ele- sons were interested in the subject from a philo- ment (root or primordial matter) which can sophical perspective and/or with respect to the change its form according to density: diluted application of techniques (engineering) but also into fire, it may condense to wind and, by fur- motivated always by the specific problems (e.g., ther condensation, into water and finally into 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 15 soil and rocks. This was very likely the first cloud is thrust up into the upper atmosphere which “poetic” description of the idea that all material is colder, because the reflection of the sun’s rays on Earth is subject to cycling, where “dilution” from the earth ceases there, and upon its arrival there and “condensation” are the driving processes. the water freezes. They [Anaxagoras] think this ex- plains why hailstorms are more common in summer Empedocles of Acragas (495-435 BC) introduced and in warm countries.” the four elements earth, water, air and fire, the list was then extended by Aristotle (384-322 BC) The Greek philosopher Anaxagoras of Klazome- by a fifth one, the aether (explaining the heav- nai (500-428 BC) came to Athens as a young enly, in Greek ). Aristotle asked in his man, more than 100 years before Aristotle. Ques- Meteorologica: “Since water is generated from tioned on what he was born for he answered: air, and air from water, why are clouds not formed “To observe sun, moon and heaven” (Diogenes in the upper air?” He explained as follows (Aris- 1921). His philosophy is based on the Eleats and toteles 1923: I, 9, 346b/26): “But when the heat Empedocles. With his doctrine that meteorolog- which was raising it leaves it, in part dispersing ical phenomena were caused by sun activities to the higher region, in part quenched through he was in contradiction to the generally prevail- rising so far into the upper air, then the vapour ing opinion. Anaxagoras’ theory is amazingly cools because its heat is gone and because the correct but Aristotle wrote (Aristoteles 1923: I, place is cold, and condenses again and turns 12, 348a/14): “… this is just opposite to what from air into water. And after the water has formed Anaxagoras says it is. He says that this hap- it falls down again to the earth. The exhalation pens when the cloud has risen into the cold air, of water is vapour: air condensing into water is whereas we say that this happens when the cloud. Mist is what is left over when a cloud cloud has descended into the warm air …”. condenses into water, and is therefore rather a sign of fine weather than of rain; for mist might Aristotle, in contrast to this error, however, con- be called a barren cloud. So we get a circular tributed many accurate explanations of atmos- process that follows the course of the sun … pheric phenomena. The description of the wa- From the latter [clouds] there fall three bodies ter cycle (reasons for rain), as presented above, condensed by cold, namely rain, snow, hail … could have been taken from a modern textbook. When the water falls in small drops it is called Archimedes of Syracuse, Sicily (287-212 BC) in- a drizzle; when the drops are larger it is rain … directly contributed with his buoyancy princi- When this [vapour] cools and descends at ple to the design of the hot-air balloon, an in- night it is called dew and hoar-frost.” vention which added much to our knowledge of the vertical structure of the atmosphere in the From his Meteorologica we know that Aristo- 19th and the beginning of the 20th century, and tle believed that weather phenomena were to the basis for theoretical investigation of the caused by mutual interaction of the four ele- buoyant rise of cumulus clouds. Theophrastus ments (fire, air, water, earth), and the four prime (about 372-287 BC), the successor of Aristotle contraries: hot, cold, dry and moist. Aristotle in the Peripatetic school, a native of Eresus in frequently argued against ideas which were Lesbos, compiled a book on weather forecast- actually closer to the truth than his own (An- ing, called the “Book of Signs”. His work con- thes et al. 1975). E.g., he presented the views sisted of ways to predict the weather by observ- of Anaxagoras considering the cause of hail ing various weather-related indicators, such as as follows (Aristoteles 1952: 81): “Some think the halo around the moon, the appearance of that the cause and origin of hail is this: The which is often followed by rain. 16 Detlev Möller DIE ERDE

2.2 From the Middle Ages to the ed – until the chemical composition of the air and Age of Enlightenment the structure of water was discovered by Caven- dish, Scheele, Priestley, Lavoisier and others af- All “philosophies” of the Middle Ages were based ter 1770. We should not forget that solely the on ancient philosophers, new observations and estimation of volume and mass has been the fun- conclusions were not added – in contrast, due to dament of the basic understanding of chemical re- the predominance of non-scientific approaches actions and physical principles since Boyle. While (“alchemy”) there was no progress. For example, instruments to determine mass (resp. weight) and Albertus Magnus, the most prominent German phi- volume had been known for thousands of years, losopher and theologian of the Middle Ages (1193- the new instruments (thermometer, barometer) to 1280), wrote four books titled “Meteorum” fully supply us with the necessary data to test the identical with Aristotle’s books. Although weath- physical laws were only available to scientists er records had been taken at different locations as since Galileo Galilei (1564-1642). Around the early as the 14th century, meteorology did not be- year 1600, Galileo established an apparatus to come a genuine natural science until the invention determine the weight of the air and invented a of weather instruments; after Hellmann this is crude thermometer..Without contact to Galilei the called the 2nd period in the history of meteorology. thermometer was invented in Holland by Cor- Aristotle’s theory survived 2000 years: dew as a nelius Jacobszoon Drebbel (1572-1633) and first deposition from the air, despite the contradiction used in 1612 by the physician Santorio (1561- with his observation that “both dew and hoar-frost 1636), called Sanctorius of Padua (Hellmann are found when the sky is clear and there is no 1920). The Italian mathematician and physicist wind” (Aristoteles 1923: I, 12, 348b/1). Evangilista Torricelli (1608-1647), a student of Galilei, produced a vacuum for the first time and Water remained one of the four “elements”, i.e., discovered the principle of the barometer in 1643. indivisible bodies, and the idea prevailed that one Torricelli also proposed an experiment to show element could be converted into another. All sub- that atmospheric pressure determines the level of stances and materials in nature were considered a liquid (he used mercury). Torricelli’s scholar different mixtures of these four elements. As a Vincenzo Viviani (1622-1703) finally conducted consequence of this belief, all substances were this experiment successfully and Blaise Pascal transmutable into all others and were contained (1623-1662), a contemporary French scientist, car- in each of them. Each element had two qualities: ried out very careful measurements of the air pres- earth: cold and dry; water: cold and wet; fire: hot sure on Puy-de-Dôme near Clermont in France. He and dry; air: hot and wet. In his posthumous “Or- noticed the decrease of pressure with altitude and tus medicinae i. e. initia physicae inaudita” (1652) concluded that there must be a vacuum in high Johann Baptist (Jan) van Helmont (1577-1644) altitudes. In 1667 Robert Hook (1635-1703), an put forward the idea that all substances, except assistant of Boyle’s, invented an anemometer for air, were derived from water. measuring wind speed. In 1714 Gabriel Daniel Fahrenheit (1686-1736), a German glassblower and The observation that remote water (materia prima) physicist, born in Danzig and later working in Hol- only comes from the atmosphere (atmospheric land, worked on the boiling and freezing of water, water) certainly promoted the experiments to get and from this work he developed a temperature the philosopher’s stone from it. Despite much scale. Horace-Bénédict de Saussure (1740-1799), progress at the beginning of the 17th century, the a Swiss geologist and meteorologist, invented the belief of convertibility between air and water, and hair hygrometer for measuring relative humidity in water and soil (and vice versa) was widely accept- 1780. According to Umlauft (1891) Grand Duke 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 17

Ferdinand II of Toscana (who reigned 1621-1670) called ‘water controversy’ in 19th century. With re- invented the first hygrometer (Torricelli was his spect to the discovery of the chemical composition court mathematician). Benedetto Castelli (1578- of water, three scientists must be regarded as candi- 1643), a friend of Galilei’s, used the first rain gauge dates (Kopp 1869): Cavendish, who was probably in 1639 to measure the rain depth. the first (in 1781) to carry out experiments to form water by combining phlogiston and dephlogisticat-

It is not known which is the oldest meteorolog- ed air (O2), also called good, pure, vital, fire air (in ical instrument, likely the wind fane (700 BC in German: gute Luft, Dephlogiston, Lebensluft, reine Babylon). The poet Terentius Barro (185-159 Luft, Feuerluft etc.); Watt, who formulated the com- BC) used it on his estate. But it was not until position of water in 1783 in a similar way to Caven- Ignacio Denti combined several wind vanes dish; and finally Lavoisier, who, in 1783, made the with a wind rose in Bologna and Florence in the first public announcement that water consisted of

1570s to show exactly the incoming wind direc- inflammable air (H2) and dephlogisticated air (O2). tion. A rain gauge was first used in 400 BC in India, and independently in Palestine (ca. 100 Nowadays it is hard to understand what phlogis- AD), and with a network in Korea (1442) for ag- ton meant. The phlogiston theory, founded by ricultural purposes (Hellmann 1920). The first Johann Joachim Becher (1635-1682) and devel- commercially produced self-registering pluvio- oped further by Georg Ernst Stahl (1660-1734) – meter (Latin pluvia = rain) was introduced by both of them German chemists –, was to some ex- Christopher Wren (1632-1723) in London in 1663. tent derived from the old belief that there was a fire element and that all combustible bodies contained It is very likely that the first physical treatment a common principle (element), phlogiston (which of rainwater was performed by the great Arab in Greek means “flammable” or “inflammable”), scientist Abd al-Rahman al-Khazini who worked which is released in the process of combustion. in Merv (former Persia, now Turkmenistan) be- Substances rich in phlogiston, such as wood, burn tween 1215 and 1230 and who was a student of almost completely; metals, which are low in phlo- (Abû‘r-Raihân Muhammad ibn Ahmad) al-Bîrûnî giston, burn less well. The phlogiston theory cre- (937-1048) who first introduced the weighing of ated great confusion and essentially empeded the stones and liquids to determine their specific weight understanding of the chemistry of phase-transfer (Durant 1950, Hall 1973). Al-Khazini is known for processes and solid-gas reactions. Chemists spent his book “Kitab Mizan al-Hikma” (The book of much of the 18th century evaluating Stahl’s theory the Balance of Wisdom), completed in 1121, which before it was finally proved to be false by Antoine has remained a central piece of Muslim physics Lavoisier. When reading these old papers with our ever since. Al-Khazini was the first to propose the present scientific knowledge it is often difficult, if hypothesis that the gravity of bodies varies de- not impossible, to understand what the scientists pending on their distances from the centre of the meant by different terms; confusion also results earth and he defined the specific weight of numer- from attributing the same term to different ous substances and also that of rainwater to be substances (we may only conclude that in those exactly 1.0 g cm-3 (Szabadváry 1966). days such distinguishing was not always possible):

phlogisticated air for both N2 and H2, acid air (Sauer-

luft in German) for both CO2 and O2. Kopp (1869) 3. Water as a Chemical Compound accepted that phlogiston was actually hydrogen. Scheele (1777) found evidence that one unit by The debate about who was the actual discoverer volume of oxygen produces one unit of carbon of the chemical composition of water (H2O) was dioxide and defined that “Feuerluft (O2) = Phlo- 18 Detlev Möller DIE ERDE

giston + fixe Luft (CO2 )” which was wrong and into hydrogen and oxygen. Lavoisier (1790) estimat- should have be written (in the old terms) as: car- ed the composition of 100 g water as 85 g oxygen bon = fixed air (CO2) + phlogiston”, i.e., when and 15 g inflammable gas (hydrogen), which is rela- carbon is burnt, it is transformed into carbonic tively close to the correct quantities: 89 + 11. acid (CO2) while releasing “phlogiston”. Water chemistry, however, deals with the compo-

Hydrogen (H2) was probably already known to Pa- sition of natural water (or common water, to dis- racelsus and Helmont (without using the name) in tinguish it from atmospheric water). In addition, the 16th century but was often confused with other water chemistry (now often also termed aquatic combustible gases. Hydrogen was produced by the chemistry) also studies chemical reactions in wa- treatment of metals with acids, but any “flammable ter and aqueous solutions (e.g. Stumm 1990; Sigg air” was called “sulphurous”. Stahl maintained that and Stumm 1996; Stumm and Morgan 1996). Thus, phlogiston is exhausted by metals and combines it is obvious to speak of rain, snow, fog, cloud or with the acid to a flammable substance. Cavendish dew chemistry in the sense of analysing the chem- (1766), however, was able to show that the flamma- ical composition of the solution. This is the task of ble air produced by the dissolution of iron in sul- analytical chemistry as a subdiscipline of chemis- phuric acid and of zinc in hydrochloric (muriatic) acid try which has the broad mission of understanding was phlogiston itself and did not contain anything the composition of all matter. Much of early chem- of acid. Today we know that this gas is hydrogen, istry was analytical chemistry since the questions however, at that time, other flammable gases (pro- of which elements and chemicals are present in the duced for example when organic matter is decom- world around us and what are their fundamental posed: CO, PH3) were hardly distinguished. Caven- nature is very much in the realm of analytical chem- dish was the first to study this flammable air (H2) in istry. Before 1800, the German term “Scheidekunst” different mixtures with common air to investigate its (“separation craft”) was used in place of “analyti- explosion (1766). Priestley (1775) found that this cal chemistry”; in Dutch, chemistry is still general- flammable air (H2) exploded much more vehemently ly called “scheikunde”. Before developing rea- when brought together with the newly discovered gents to identify substances by specific reactions, pure dephlogisticated air (O2) than with common air. only knowledge about the features of the chemi- Cavendish (1784: 123) observed that after the explo- cals (odour, colour, crystalline structure etc.) was sion the inside of the glass vessel became dewy (“… used to “identify” substances (cf. Fig. 5). With that common air deposits its moisture by phlogisti- Lavoisier’s modern terminology of substances cation”). In explosions in which Cavendish (1784: (1790) and his mass conversation law, chemists 130) used electric sparks he found “… liquor in the obtained the basis for chemical analysis (and syn- globe …; it consisted of water united to a small quan- thesis). Carl Remigius Fresenius (1818-1897) wrote tity of nitrous acid”. This statement is most remark- the first textbook on analytical chemistry (1846) able, it forms the first evidence of HNO3 formation which is still generally valid. under atmospheric conditions by lightning. Sir Charles Blagden (1748-1820), English physicist and Cavendish’s assistant from 1782 to 1789 reported to 4. Physics of Atmospheric Waters Lavoisier about Cavendish’s experiments in 1781 (Hydrometeors) and, together with Pierre-Simon (Marquis) de Laplace (1749-1827), the great French mathematician, 4.1 Milestones of discovery he repeated Cavendish’s experiments. He was able to invert the experiment, i.e. he decomposed water This section deals with the milestones in the step- (by directing water vapour over a red-hot iron wire) wise approach to explain the formation of clouds 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 19 and rain from the beginning of the 17th until the – First cloud classification by Lamarck (1802) end of the 19th century. First it should be noted and Howard (1803), that a scientific understanding of phase-transfer processes (smelting, boiling, condensing and – Water condenses only on particles by Aitken freezing) was not achieved before the middle of (1881), the 19th century (with the development of thermo- dynamics). Black, Watt, de Saussure, Deluc and – Final evidence that clouds consist of droplets other great scientists contributed to the under- and not vesicles by Aßmann (1885). standing of the nature of water vapour, for which different terms were in use. From the early 17th century onwards a distinction was made between 4.2 The 17th century: vapours (aqueous and humid particles) and ex- Descartes and Guericke halations (solid and or liquid particles but not aqueous or humid). The ancient element “fire” was Recall that air and water were regarded as “ele- used in the sense of heat until the end of the 18th ments” convertible into each other since Aristo- century (Deluc 1787). Thus, vapour was first con- tle. The statement that water vapour is not (atmos- sidered as “little bubbles of water filled with fire”. pheric) air by René Descartes (1596-1650), also Later this was defined as fog and cloud (particles, known as Renatus Cartesius, the French philoso- vesicles etc.) and “visible vapour”. In 1806, Wil- pher, mathematician, scientist and writer, is remark- helm August Lampadius (1772-1842), professor of able as this was 15 years before the introduction chemistry in Freiberg (Saxony) still wrote (1806: of the term “gas” by van Helmont. There was 118): “Das atmosphärische freye Feuer verbindet obviously a need for a new word to name and dis- sich mit dem Wasser zu einem eigenen elastischen tinguish the laboratory airs (i.e. gaseous sub- Fluidum, dem Wasserdampf; das Feuer ist fortlei- stances) from atmospheric (common) air. This was tendes Fluidum; das Wasser wägbare Substanz proposed by van Helmont: “hunc spiritum, incog- [Atmospheric free fire combines with water to a nitum hactenus, novo nomine Gas voco [I call this specific elastic fluid, water vapour; fire is the off- entity which hitherto has been unknown by the conducting fluid; water a ponderable substance]”. new name of “gas”] (Helmont 1652).

The milestones are summarised as follows: With his book “Discours de la méthode pour bien conduire sa raison et chercher la vérité dans les – Statement by Descartes (1637) that atmos- sciences. Plus la dioptrique. Les Meteores. Et la pheric water is not air, Géometrie. Qui sont des essais de cette méthode” Descartes (1637) presented a nature philosophy – First artificial cloud/fog formation, “bubble to explain “the entire physics”. His approach is theory” (vesicles) by Guericke (1672), fully empirical and based on careful observation. He explains the nature of clouds by vapours ris- – Cloud described as a water suspension by ing from the sea (“exhalaisons & des vapours”), Le Roy (1751), their distribution (through the formation of winds) and finally their “contraction” into clouds and – First direct observation of (walking in) clouds fogs (nuës & de la brouille). As fog he defines by de Saussure (1783), the “vapours” near the earth’s surface.

– First physical theory (no water dissolution The same explanation was used by Ludwig Frie- in air) by Deluc (1787), drich Kämtz (1801-1867, Kämtz 1940), professor 20 Detlev Möller DIE ERDE of physics in Halle (Germany), and by Flamma- lished more than 10 years after the experiments, rion. Flammarion (1873) wrote: “When it [con- he stated in the first chapter of the third book densation] occurs at the level of the soil, it is (De aere ejusque origine, natura & qualitatibus termed mist. But there is no essential difference [on the air, its origin, nature and properties], between a cloud and mist.” Nowadays we call Guericke 1672a: 71, translated from the German mist a thin fog near the ground; even thinner mist edition, Guericke 1672b, see also Guericke is called ‘haze’ (atmospheric moisture or dust or 1972c): “The air, according to our idea, can be smoke that causes reduced visibility). divided into steps or regions. Each kind of cloud, heavier or lighter, keeps to its own particular one Descartes wrote that “expanding vapours pro- of these regions, in which its weight matches that duce wind and contracting vapours produce of the air. But if the air was compressed every- clouds”. It seems remarkable that Descartes also where it would be equally heavy above and be- used the terms water droplet (goutte d’eau; in low, so that clouds could not be formed in dif- Latin: gutta = drop, guttula = droplet) and ice ferent ways in different regions; but as in water particles (parcelles de glace). He argued that things either sink to the bottom or float, so the the water droplets must be perfectly ball- clouds would either descend to the earth, or go shaped (rondes) and that they are small other- up to the highest part of the air … Air is not an wise they would fall down as rain or snow. In elemental substance (non est elementum) … Air addition, he wrote that high-altitude clouds is nothing else then damping (exspiratio) or smell never consist of water droplets but of ice parti- (odor) or effluence of waters, earth and other cles. Rain is formed when many water droplets substances … Air and smell once generated from coalesce after collision (“… se touchent et elles water or other things and will never be trans- s’assemblent”). Principally, Descartes remained formed back to water but remains air.” within the philosophy of Aristotle, i.e. retained the idea of the transformation of water into air Guericke also produced clouds (nubes) and fog and vice versa. Descartes defined three ele- (nebula) by expansion of air from one flask into ments (éléments) or particles (parties), those another one which had been evacuated; he from fire (very fine), earth (coarse) and air (fine), wrote (in the eleventh chapter on p. 88) the fol- corresponding to the heat, solid and liquid/gas- lowing phrase which seems to me the first sci- eous state of matter. He used the term matter entific statement that cloud particles are bub- (matière) as a general term and for him the par- bles or vesicles (not droplets; in Latin vesica = ticles are divisible in an unlimited way. To me it vesica and vesicula = vesicle): “Quod tantò appears that he was the first to clearly describe magis apparet, quantò magis vitrum interne hu- the phenomenology of the mixed-phase cloud miditatibus refertum est; tunc enim plures ac processes and to state that clouds contain ice copiosiores exurgunt bullulæ, ita ut (…) nebu- particles also in the summer. lam constituant; quæ per intromissionem ali- quid aëris … tunc nebula illa in nubes dis- Some 20 years after the publication of Les pergitur. [This effect appears so much clearer Météores, between 1650 and 1662, Otto von Gue- the higher the humidity in the glass flask is; ricke (1602-1686), mayor of Magdeburg, invent- then numerous and larger bubbles producing ed the air pump and worked on his famous ex- fog are formed. By running a little bit of air into periments concerning the physics of the air. In the glass … the fog dissipates into clouds].” addition, he studied the formation of clouds. In his famous book “Experimenta nova (ut vocan- While later scientists argued that the water par- tur) Magdeburgica de vacuo spatio” (1672), pub- ticles may only exist in clouds when they 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 21

“swim”, the “bubble theory” was almost ac- The German naturalist Christian Gottlieb cepted. However, even when the bubbles (or Kratzenstein (1723-1795), known for his stud- vesicles) are filled with common air, the cloud ies of electricity impacts on humans, first meas- vesicles must be heavier than the medium in ured the size of cloud droplets by comparing which they swim (Kämtz 1840). It was not until them with a hair, in 1744 or even before (Kratzen- the end of the 19th century that the long debate stein 1744); arguing that the thickness of a hair whether cloud particles are droplets or vesi- is 1/300 inch, he obtained a size of 0.00028 inch, cles, started by Descartes and Guericke, was very similar to the later estimate by Horace Béné- ended by Aßmann’s microscopic observations. dict de Saussure (1740-1799), another Swiss natural scientist (mainly geologist), who pub- lished the book “Essais sur l’hygrométrie” 4.3 Concepts of the 18th century (1783). The latter constructed and used the first hair hygrometer which consists of a hair free of Charles Le Roy (1726-1779), French professor grease fixed to the frame at the top and to a for medicine in Montpellier and Paris, used the weight at the bottom. However, he did not know term “solution” to describe fog and clouds that the measurement result represented only the (1771). He mentioned the experiment in which ice relative humidity. De Saussure tried to estimate is placed in a dry glass, which soon becomes the size of cloud droplets with a magnifier which covered with very small drops of water. The tem- resulted in between 0.00022 and 0.00036 inch; 3 perature, which we now call dew point, is called assuming Prussian “Zoll” for inch, i.e. 2 /5 cm, “le degré de saturation de l’air” by Le Roy. the size corresponds to 8 μm which comes very Dew, he said, forms everywhere in the atmos- close to a mean cloud droplet we measure to- phere near the ground. And, he pointed out that day. De Saussure distinguished between four “dry air” on a summer day can contain more types of “vapours” (vapeurs): the “pure elastic water than very “moist air” in winter. vapour” (vapeur élastique pure) just after the evaporation of water, the “dissolved elastic va- Jean-André Deluc (1727-1817), Swiss natural pour” (vapeur élastique dissoute), the water va- scientist, was the first to observe clouds dur- pour proper, and finally two types of condensed ing his many walks in the Alps. In his famous water, first the “vapour vesicles” (vapeur vé- book “Idées sur la météorologie” (1786) he de- siculaire), which he describes as very fine par- scribed the reasons for evaporation and the ticles (mist in modern terms), and finally “solid formation of “aqueous vapours”; he called hy- vapour” (vapeur concrète), likely a step in form- drometeors “gutterable water” (translated into ing precipitation (he wrote: “When finally the “wässerigte Dünste”, “Wasserdünste” and elastic vapours or vesicles condense to small “tropfbares Wasser” in the German edition). He solid droplets …” ). French concret means concluded that the atmospheric water vapour (chemically) ‘solid’, as opposed to ‘fluid’. It is is identical with that from boiling water. This hard to understand what de Saussure means by correct conclusion (i.e. phase transition), based “solid droplets” – perhaps frozen water, i.e. ice on a friendly contact with James Watt (1736- particles? Or could it mean haze in the sense of 1819), replaced the former hypothesis that wa- condensation nuclei? Clouds and fog (clouds ter vapour was formed by the “dissolution of at the Earth’s surface) consist of many such water in air”. He was the first to correctly de- vesicles (he walked and observed droplets by scribe the “water-fire” relationship in the sense magnifier). Saussure, however, remained an ad- that vapour is a composition of water and heat herent of the “dissolution theory” (transforma- or dissolution of water into vapour. tion of water into air). 22 Detlev Möller DIE ERDE

The understanding of cloud formation at the end lished his results in 1875 and Aitken published his of the 18th century can be described by the fol- in 1880. They conducted almost identical experi- lowing scheme: ments, obtained very similar results and provid- ed similar explanations: Vapours condense on solid Water (as body: bulk) ї Vapour (steam; airborne nuclei. Nevertheless, Coulier had diffi- invisible) їHaze (only the German Dunst culty explaining some of his later results by the “condensation nuclei hypothesis”; he thought was used; visible) ї (Fog and) Cloud that this hypothesis was not generally valid. (ўice particles) ї Rain or snow or hail Aitken only noticed Coulier’s paper in 1881. He (by cloud particle collision) repeated some of Coulier’s experiments and was then able to explain all of his and Coulier’s results Deluc characterised vapour as “fine water par- by means of the “condensation nuclei hypothe- ticles” (in modern terms: molecules), Dunst sis”, which he considered as generally valid. This (haze) as coarser water particles, likely identi- work led to the continuing study of heterogene- cal with Saussure’s “vapeur concrète” (in mod- ous nucleation and the development of conden- ern terms: haze particles, i.e. atmospheric mois- sation nuclei counters. Aitken built the first ap- ture or dust or smoke that causes reduced vis- paratus to measure the number of dust and fog ibility; Russell (1895: 232) presents the first ex- particles in the atmosphere. One of his experi- planation of haze as a scientific term: “This haze ments, conducted with a self-designed apparatus, may be taken to be caused by the aggregated provided the first evidence of new particle forma- nuclei of dust left after evaporation of the wa- tion in the atmosphere. As early as 1874 (but only ter which condensed upon them”). published in 1880), Aitken had concluded that when water vapour condenses in the atmosphere, it must condense on some solid particle; without 4.4 Atmospheric water in the 19th century the presence of dust or other aerosol particles in the air, there would be no formation of fog, clouds Deluc’s theory was the most advanced in Geh- or rain. Despite the fact that others had arrived at ler’s “Physikalisches Wörterbuch” (1825-45). this conclusion even earlier (see below), Aitken Kämtz (1840) discusses the reason why cloud is one of the founders of aerosol science; today, drops remain suspended in the air, even if they his name has been given to the smallest atmos- are heavier than air (he still adhered to the vesi- pheric aerosol particles (“Aitken nuclei”). Aitken cle theory, but inside the air and not in other – had no doubt that the nuclei were from two class- lighter – gases), and concluded that this was by es of particulates, sea-salt and the products of ascending air. In spite of a rapid development of combustion (remarkably, evidence for sea-salt in meteorology to a scientific discipline at the be- the sub-μm range in cloud condensation nuclei, ginning of the 19th century (Humboldt, Brandes, CCN, was only found 100 years later). Dove) it was not before 1870 that new fundamen- tal insights into cloud formation were gained. The last question to be answered correctly in the 19th century was to resolve the problem “vesicle Paul-Jean Coulier (1824-1890), a French pharma- theory versus droplet theory”. Augustus Volney cist, and John Aitken (1839-1919), a Scottish phys- Waller (1816-1870), a British physiologist, was icist and meteorologist working in England, con- the first after de Saussure to directly observe ducted the first elementary experiments and ob- cloud droplets and concluded (by optic pheno- servations on the role of fine airborne particles in mena) that they consisted of drops and not ves- vapour condensation processes. Coulier pub- icles (Waller 1847). Forty years later Adolph 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 23

Richard Aßmann (1845-1918), German meteo- brought dust which was so much like sulphur that, rologist, known for his aspiration psychrometer when thrown into fire, it produced the same smell, and founder of aerology, first director (1905- and that, when mixed with spirits of turpentine, it 1914) of the Royal Prussian Aeronautic Observ- produced a liquor with an odour just like that of atory at Lindenberg (Brandenburg), observed balm of sulphur; of course the close neighbour- cloud droplets on Mount Brocken in November hood to Iceland’s volcanoes is sufficient to explain 1884 at different levels within the cloud, using this occurrence (reported here after Flammarion the best microscope available at that time 1874). In any case, these texts suggest that the per- (Aßmann 1885). He also concluded that after sons must have collected rain water for “chemical evaporation of the droplets he was unable to see consideration” (remember that rain collection for any residuals and therefore the CCN had to be estimation of the rainfall amount had been imple- smaller than 1 µm. The most astonishing circum- mented hundreds of years before). The matter (for- stances about the vesicle theory are the fact that eign bodies) was either regarded as suspended in there was almost a complete absence of a theo- the atmosphere in a state of mixture or as elements ry of their formation and the fact that established “which pervade the atmosphere in a state of solu- scientists like Jöns Jakob Berzelius (1779-1848) tion” (Prout 1834: 347). The nature of the parti- and Rudolf Julius Emanuel Clausius (1822-1888) cles was found to be of vegetable origin or from supported the vesicle existence. meteoric stones or aerolites, from volcanoes and soils, but meteorites too.

5. The Chemistry of Atmospheric Water Most probably the first rain water samplings (es- (Hydrometeors) pecially after lightning) for “chemical” treatment (probably distillation) were carried out by alche- 5.1 Early observations and mist members of the Rosicrucians (Rosencreut- the era of alchemy zer) in their quest to find the “philosopher’s stone” (Kopp 1886). Since Aristotle it was known The observation that substances other than wa- that dew only appeared in calm and serene nights. ter (so-called foreign bodies) were connected with Dew which had fallen from the clear sky was re- precipitation was known since Aristotle. Differ- garded as matter from the sun or even from stars. ent colours and odours had been described, most- Thus, alchemists treasured dew because they ly in connection with fog and mist. Showers of believed it to be sideric and a potential source of blood, earth, sulphur, plants, frogs and various the philosopher’s stone. kinds of animals as well as coloured snow can be found in the literature (first in Homer). These Christian Ludwig Gersten (1701-1762), a German phenomena, connected with blooms, parts of in- professor of mathematics in Gießen, was the first sects, pollen and dust, were first identified by the to find out, based on observations, that dew did French naturalist Nicolas Claude Fabri de Pei- not fall from the heavens but ascends from earth, resc (1580-1637) and later by René-Antoine Fer- especially from plants (Gersten 1733). Charles chault de Réaumur (1683-1757). The Danish Ole François de Cisternay du Fay (1698-1739), a Worm (1588-1655), also called Olaus Wormius, French chemist (known for finding two kinds of reported that on 16th May 1646 there was a heavy electricity), wrote: “Glass and porcelain collected shower in Copenhagen that contained dust ex- much dew, while polished metal surfaces collect- actly like sulphur. Simon Pauli the younger (1603- ed almost none” (du Fay 1736). Also in 1736, 1680), a German physician living in Denmark, Petrus van Musschenbroek (1692-1761), a Dutch states that on 19th May 1665 a storm in Norway scientist in Leiden, reported on dew observations 24 Detlev Möller DIE ERDE

Fig. 1a Plate 4 from Mutus liber (1677). It shows an alchemist and his wife wringing out a cloth and collecting (atmospheric) water in a bowl. In the background there are five clothes stretched among four stakes. It is likely that dew is collected here despite the fact that similar collectors were used later for rain water sampling but with a bowl below (!) the cloths. / Platte 4 aus Mutus liber (1677). Ein Alchemist wird mit seiner Frau gezeigt, welche ein Tuch auswringen und dabei (atmosphärisches) Wasser in einem Kolben sammeln. Im Hintergrund sind fünf auf jeweils vier Pflöcke gespannte Tücher zu sehen. Wahrscheinlich wurde Tau gesammelt, obwohl später ähnliche Sammeleinrichtungen für das Sammeln von Regenwasser genutzt wurden, wobei aber ein Gefäß unter dem Tuch angeordnet wurde. 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 25

Fig. 1b Plate 9 from Mutus liber (1677). This figure is similar to Plate 4 (Fig. 1a) in the sense of showing (different) collectors and the sampling procedure. In Plate No 9 (identical with No 12) we see the couple filling water from the sampling bowl into a flask. Rain is seen in the background. The wife passes the flask to Hermes who will bring it to the laboratory (?). Because (almost very similar) figures with such “samplers” were found in many alchemistic books, we may assume that rain water had been sampled long before but nothing is known on chemical treatment because of the secrets in that field. / Platte 9 aus Mutus liber (1677). Das Bild ähnelt der Platte 4 (Fig. 1a) bezüglich des Zeigens von (unterschiedlichen) Sammelvorrichtungen und der Probenahmeart. Auf Platte 9 (identisch mit Nr. 12) sehen wir das Paar beim Abfüllen von Wasser aus dem Sammelgefäß in einen Kolben. Regen ist im Hintergrund symbolisch zu sehen. Die Frau übergibt Hermes den Kolben – der ihn wohl in das Laboratorium bringt (?). Obwohl (zumeist völlig identische) Bilder dieser Art in vielen alchemistischen Büchern gefunden werden, dürfen wir annehmen, dass Regenwasser schon lange vorher gesammelt wurde; allerdings ist wegen der Geheimhaltung nichts über dessen chemische Behandlung bekannt. 26 Detlev Möller DIE ERDE at Utrecht and confessed that “he did not un- Nitrate (and nitrite) has been found in dew only re- derstand why dew collects on some surfaces far cently, in quantities much higher than expected only more than on others”. He carried out many dew from dry deposition. Acker et al. (2007) systemati- collection experiments and stored a sample 24 cally studied the formation of nitric and nitrous acid years in a flask without changes. Musschen- in dew and explain it by heterogeneous formation broek’s “Elementa Physica” (1726) played an due to the reaction of NO2 with water surfaces (Ack- important part in the transmission of Isaac New- er and Möller 2007). There is another remarkable ton’s ideas on physics to Europe. phrase, showing us the reaction between sea salt

and dew (i.e. NaCl + HNO3, see Möller and Acker Le Roy carried out dew experiments in 1751 in 2007): Johann Heinrich Pott (1691-1777; 1746), Paris, and Michael Hube (1737-1807), Polish roy- German pharmacist and chemist in Berlin, quoted al secretary in Warsaw, considered dew with re- his compatriot Johann Heinrich Cohausen (1665- gard to the dissolution theory. Hube (1790), 1750), physician in Münster, who utilised van Hel- Deluc (1787) and later Lampadius (1793) faught mont’s belief that volatile salts (salts that had an against this theory. Lampadius was probably the odour or that decomposed readily when heated) first to state that the temperature difference be- constituted the vital spirit or the breath of both tween the earth and the air layer above was im- animals and plants: “Dem Meersalz von den Küsten portant for dew formation (quoted after Gehler). Hispaniens entzog er allen Geschmack, indem er es während wenigstens 40 Tagen im feinsten Tau- Rain and dew were considered as “materia pri- Geist digerierte und putrefizierte; daraus erhielt er ma” (or “remota”). The Rosicrucians also ein völlig neues Salz … von leicht bitterem Ge- called themselves “Frères de la Rosée Cuite” schmack und von einiger Ähnlichkeit mit der ni- (i.e. brethren of the boiled dew), the Latin word trosen Natur … (He deprived the sea salt of the ros (in French rosée) meaning dew (Waite 1887). coasts of Hispania of all its taste [i.e. that of com- Hence, alchemists attributed high importance to mon salt by escaping HCl] by digesting it and pu- the dew. The sampling of dew and rain (for that rifying it for at least 40 days with finest spirit of dew purpose) is illustrated by beautiful figures in the [probably HNO3 from dew salt] and found an en- “Silent Book” (“Mutus liber”) in 1677 (Fig. 1a, tire new salt … of slightly bitter taste which showed 1b), better known as Chemica Curiosa (1702). It some resemblance to nitrous nature…[i.e. is certain that the alchemists collected dew; the NaNO3])” (Pott 1753: 229). same samplers were used in the 19th century (Fig. 2). The plate which follows in Mutus Liber True alchemists never published their findings in (not shown here) shows a couple in the labora- books; their secrets were passed on from the mas- tory distilling the water collected and sampling ter to the student. Most authors of alchemist trea- the remaining “dew salt” with a spoon. It is like- tises are simply writers, who often were also ly that the alchemists found nitre (nitrate) in dew known for novels. Nevertheless, we must assume because Johann Lorenz von Mosheim (1693- that these persons had contact to alchemists work- 1755) wrote (Mosheim 1726): “Dew, the most ing in laboratories. E.g., Savinien Cyrano de powerful dissolvent of gold which is to be Bergerac (1619-1655), actually Hercule Savinien found among natural and non-corrosive sub- de Cyrano de Bergerac, a writer in Paris, de- stances, is nothing else but light coagulated and scribed in his novel the following situation digested in its own vessel during a suitable (Bergerac 1657, see Fig. 3): “Je m’estois attaché period, it is the true menstruum of the Red tout autour de moy quantité de fioles pleines de Dragon, i.e. of gold, the true matter of the Phi- rosée et la chaleur du soleil qui les attiroit m’esleva losophers” (quoted after Waite 1887: 6). si haut qu’à la fin je me trouvai au dessus des plus 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 27

Fig. 2 Dew sampler used by Wells. From “The Dew-Drop and the Mist or, an Account of the Nature, Properties, Dangers, and use of dew and mist in various parts of the world” (1847: 28), published in London anonymously (115 pp.), but likely by Charles Tomlinson (1808-1897), who published later (1867) a very similar title: „The Dew-Drop and the Mist: An Account of the Phenomena and Properties of Atmosphere“ (346 pp.). / Tausammler, wie ihn Wells benutzte. Aus: „The dew-drop and the mist or, an account of the nature, properties, dangers, and use of dew and mist in various parts of the world“ (1847), S. 28, anonym publiziert in London (115 S.), wahrscheinlich aber von Charles Tomlinson (1808-1897), der später einen ähnlichen Titel publizierte: „The Dew-Drop and the Mist: An Account of the Phenomena and Properties of Atmosphere“ (346 S.).

hautes nuées [I put around me a lot of phials full majales, salia vestra… creditis me hoc vostro of dew, and the heat of the sun, attracted by it, turpiloquio tristitia effici! [Prepare your rain and drew me to altitudes above the highest clouds]” May water, your salts … believe me that misery (quoted after Canseliet 1991: 94). creeps over me with your blather!]”

George Starkey (1628-1665), who called him- The “dew sampler” shown in Fig. 1a may also self Irenaeus Philalethes, a British alchemist have been used for rain water collection set below (Robert Boyle was a student of his) scoffs at a vessel or similar device for water sampling as de- the use of “water which has fallen from heav- scribed by Marggraf 100 years later (cf. next sec- en” (Philalethes 1667; quoted after Canseliet tion). Similarly, Evelyn’s phrase “… clean linen be 1991: 94): “Tractate aquas vestras pluviales, spread all night in any court or garden, the least 28 Detlev Möller DIE ERDE

earth, partly seemed to consist of common salt” (quoted after Kopp 1843: 255). This looks to me as the first evidence for sea salt (NaCl) in pre- cipitation. However, for Borrichius (he referred to Dickinson and even to Newton) it was the confirmation of the ancient hypothesis of water convertibility (Kopp 1843). Edmund Dickinson (1624-1707), physician of King James II, intensely interested in alchemy and chemistry and a much respected person in that time, distilled water a hundred times and always found earth after evap- oration, which he interpreted as transmutation (Dickinson 1686). It is known that Newton owned an annotated and dog-eared copy of Dickin- son’s alchemical book; he expounded his corpus- cular theory of light but also speculated on al- chemical transmutation (Newton 1704). It was not until 1732 that Herman(nus) Boerhaave (1668- 1738), a Dutch alchemist, concluded for the first time that the earth remaining after the distillation of rain water originated from dust which is per- Fig. 3 Copper plate from “L’histoire comique con- manently present in the atmosphere and depos- tenant les états et empires de la lune” by ited into the vessel (Boerhaave 1732). Cyrano de Bergerac (1657) showing a man ascending into the air with vials filled with Andreas Sigismund Marggraf (1709-1782), German dew. / Kupferplatte aus „L’histoire co- chemist in Berlin, collected and analysed rain and mique contenant les états et empires de la lune“ von Cyrano von Bergerac (1657), die snow water for purely analytical interests between einen aufsteigenden Mann zeigt, an dessen 1749 and 1751 in Berlin; he also analysed different Gürtel Phiolen gefüllt mit Tau hängen. natural (potable) waters to check their quality (Marggraf 1753). He also found ammonium, be- cause of its odour, after repeated distillation of rain water. Altogether, he found in rain water (by iden- infested as to appearance: but especially if it hap- tifying the crystals): nitrate (saltpetre), calcium, pens to rain, … dust dancing upon the surface of sodium and chloride (common salt), and organic it …” can be interpreted as the first description of substrate (“sticky and oily brown remains”). He as- a “deposition gauge” (Evelyn 1661: 32). sumed that its origin was from salty and earthy com- ponents. He also found the rainwater to be rotting. In snow, he found more hydrochloric acid than nitric 5.2 Precipitation chemistry acid, and vice versa in rain (Fig. 4). Marggraf, how- ever, also found “earth” several times, i.e. silica and Sampling and treatment of precipitation was first lime, after distillation of pure water. Therefore, he performed by Ole Borch, latinised to Olaus Bor- also confirmed the transmutation idea. Boer- richius, (1626-1690), Danish alchemist, in 1674: haave’s objection that the earth found in water was “100 pounds of snow or rain or hail water, evap- from atmospheric dust was “disproved” by Marg- orated in a vitreous vessel, transmuted into dusty graf by a distillation in a hermetically closed alem- 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 29

Fig. 4 Rain water chemical composition (among other natural waters) from Berlin, Marggraf 1753: 157 Chemische Zusammensetzung von Regenwasser (neben anderen natürlichen Wässern) aus Berlin, Marggraf 1753: 157

bic. However, Lavoisier proved (1770), by exact glass vessel for a long time is due to the dissolu- weighing, that the “earth” after boiling water in a tion of glass. Nevertheless, I assume that an 30 Detlev Möller DIE ERDE

Tab. 1 Early reports on precipitation sampling. If no source is given in the bibliography, cited after Ludwig 1862; see also Gmelin 1852: 836-839 / Frühe Berichte über Niederschlagsmessungen. Wenn in der Bibliographie keine Quelle angegeben wird, zitiert nach Ludwig 1862; s. auch Gmelin 1852: 836-839

Year What and were Author (see references)

1814 Rain Stark 1814 Paris, hail Girardin 1824 Rain Zimmermann 1825 Bad Salzuflen, rain Brandes 1834 Freiberg, rain and snow Lampadius 1834 Rain Bohling 1842 Eastern Pomerania, snow Bertels

absorption of NH3 and CO2 (both gases produce permanent companion of ammonia in the air. Be- different carbonates and carbamates when dis- fore Liebig’s findings, there was a number of stud- solved in water) also occurred as a laboratory arte- ies in precipitation chemistry in the early 19th cen- fact, given the high ammonia concentration in the tury, all from Germany, with one exception ambient air (100 years later Smith (1879) wrote that (Tab. 1). All these early rain studies were based the air of towns was full of ammonia). on evaporation. Stark (1814) found lime (Ca) in rain. Zimmermann’s analysis is remarkable (1824), In the 19th century, rain water sampling began af- he detected metals (Mn, Fe, Ni), HCl and organic + ter Liebig’s formulation of the mineral theory matter (“pyrrhin”) for the first time (beside NH4 , which held that plants take up nitrogen as ammo- H2CO3, K, Ca and Mg). In 1825, Simon Rudolph nia, carbon as carbonic acid and sulphur as sul- Brandes (1795-1842), a German pharmacist (not to phuric acid from the air for their nutrition (mineral be confused with the German meteorologist Hein- theory, see Vogel 1883). Justus von Liebig (1803- rich Wilhelm Brandes)found between 0.8 (in May) 1873), German chemist, is known as the “father of and 6.5 ppm (in January) total dissolved material + the fertilizer industry”; he is regarded as one of and identified NH4 , NaCl, CaCl2, CaHCO3, CaSO4, the greatest chemistry teachers ever. In 1824, at MgSO4, MgCl2, MnO, FeO, and organic matter. the age of 21, with Humboldt’s recommendation, The substance first identified by Zimmermann and Liebig became a professor at the University of called “pyrrhin” was characterised some years lat- Gießen, where he established the world’s first er (1828) by Vogel as not a specific substance but major school of chemistry. In the years 1826 and as water-soluble organic matter in general. Lam- 1827 Liebig collected 77 rain water samples in padius (1837) stated that pyrrhin was nothing Gießen and detected nitrate and ammonium (Lie- else than “Humus der Sonnnenstäubchen, vom big 1835). Liebig (1865) wrote that contemporary trockenen Lande aufgeweht” (in modern Eng- studies had shown that nitric acid was always lish: “humic-like substances from atmospheric contained in rain and often more in weight than aerosol originating from soil dust resuspen- ammonium and that, as a result, nitric acid was a sion”). With regard to the organic matter which 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 31

Brandes had found he distinguished two kinds: canic ash), grains of sand, ammonia, diatoms, one soluble in water and another, “animalic”, pyrite and organic matter were found. soluble in potash. The term “organic chemis- try” was first used by Berzelius in 1806 in Swed- Robert Angus Smith (1817-1874) was a Scottish ish (organisk kemie; Walden 1941). Before chemist who investigated numerous environmen- that, “organic matter” was called “organised” tal issues. He was a scholar of Liebig’s and stud- or “animal” matter. In Germany, the first text- ied rain chemistry in 1848 in Manchester (Fig. 5), book on “Organische Chemie” was published for the first time from an air pollution point of view. by Gmelin in 1817. Marggraf (1753) had al- He published his findings on different kinds of rain ready identified organic matter in the rain of for the first time in 1852 (since that time the term Berlin and called it “particules visqueuses & “acid rain” has been used). He was appointed Queen huileuses” (viscous and oily particles). Victoria’s first inspector under the Alkali Acts Ad- ministration of 1863. His famous book (Smith 1872) First quantitative estimates of rain water compo- was the first monograph on air chemistry. nents were made in 1848 in Wiesbaden by Fre- senius. In the 1850s, a number of French scien- In 1897 Henriet’s book was published in Paris in tists started rain and deposition studies (almost the style of a modern monograph on atmospher- all because of agro-chemical interests, hence fo- ic chemistry (H. Henriet was a chemist at the cused on nitrogen, see Tab. 2). Montsouri Observatory near Paris; he published many papers on ozone and other air constituents). In addition, hail studies were popular (e.g. Gi- He was probably the first to use the term rardin 1839) and the book (1854) by Pieter “chimique de l’atmosphère”. In his introduction Harting (1812-1885), Dutch chemist and bota- he emphasised the importance of air chemistry nist in Utrecht, was reviewed by an unknown monitoring. Rain water sampling started along author (1856) with the interesting finding that with trace gas measurements in 1881 at the Mont- hailstones always contained a white opaque souris Observatory, in a park close to the centre nucleus (often several) in the middle and air of Paris (the station is known world-wide for the bubbles; in the melted water earthy parts (vol- first quantitative ozone monitoring).

Tab. 2 French precipitation studies around 1850 / Niederschlagsstudien in Frankreich um 1850

Year Author (see references) Place

1850 Marchand Fécamp 1851-52 Barral Paris 1853 Boussingault Paris 1855 Filhol Toulouse 1850’s Pierre Caën 1852-53 Bineau Lyon 1850-52 Bobière Nantes 32 Detlev Möller DIE ERDE

Fig. 5 Residual from evaporated rain water, from Smith 1872: 382ff.: “In the rain of Manchester there is confusion of crystals; although sulphates are prominent. I do not see crystals of common salt. It would appear that decomposition takes place … when sulphuric acid passes into the atmosphere in towns it probably seizes part of the sodium of the common salt in the same way, and so liberates hydrochloric acid – an alkali-work continually in action.” / Rückstände von abgedampftem Regenwasser, aus Smith 1872: 382ff.: „Im Regen von Manchester befindet sich ein Gewirr von Kristallen; wobei Sulfate dominierend sind. Ich kann keine Kristalle von Kochsalz erkennen. Es scheint, dass eine Zerlegung stattgefunden hat … wenn Schwefelsäure durch die Luft der Städte zieht und wahrscheinlich einen Teil des Natriums des Kochsalzes in derselben Weise traktiert und dabei Salzsäure freisetzt, wie es kontinuierlich in einer Alkalifabrik abläuft.“

The first long-term rain sampling monitoring 1880 he was awarded a professorship in Tokyo started in 1853 at the agricultural research site in and stayed in Japan for 12 years. From 1893 until Rothamsted (Lawes et al. 1882). After 1860, a his death in 1911 he was the director of the Möck- number of long-term studies was implemented at ern experimental station in Saxony. Several rain different locations (Tab. 3). Oskar Kellner (1851- water monitoring stations existed in the first 1911), a German chemist, together with Liebig and half of the 20th century using so-called deposi- Hellriegel considered as a pioneer in agricultur- tion gauges (see, e.g., Ashworth 1933). After al chemistry and called the “father” of Japanese World War II, rain water studies from an agri- agricultural chemistry, came to Japan in 1881 cultural point of view first started in Sweden in where he conducted first precipitation chemis- 1947 (Egnér et al. 1949) to study nitrogen (as + - try measurements from 1883 to 1885. He had NH4 and NO3 ) and sulphur input. To my been an assistant of Wolff’s at Hohenheim; in knowledge, the last to quote Marggraf’s early 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 33

Tab. 3 First long-term precipitation chemistry monitoring (cited after Warington 1889), in ppm as nitrogen / Die erste chemische Langzeit-Niederschlagsbeobachtung (zitiert nach Warington 1889), bezogen auf Stickstoff Lincoln, Germany Montsouris Rothamsted, Newzealand Tokyo (2 yr) (13 yr) (10 yr) London (3 yr) Nitrate 0.47 0.70 0.150 0.085 0.19 Ammonium 0.146 0.18 0.096 0.126 0.84

finding that nitrate is contained in rain was point of view, and therefore he did not analyse any Torstensson (1954) (wrongly written as “Mark- other substance (also in rain, snow and dew). No graf” and without bibliographic data). other cloud studies are known from the 19th cen- tury, except for urban fog (called town fog in the Remarkably, scientists from many disciplines were 19th century, see next section). Only after World interested in the chemical composition of rain and War II cloud studies were initiated, first in the snow water in the mid-19th century and, conse- USA (Houghton 1955), later in Germany (Mrose quently, reviews on original studies can be found 1966), Russia (Petrenchuk and Drozdova 1966) and in several books, e.g. a review on precipitation Japan (Okita 1968). Systematic studies around the chemical studies (in Pierre 1859 in French, almost world began in the 1980s: for example in Italy (San- completely translated into English and published dro Fuzzi), California/USA (Jeff Collett, Daniel in Smith 1872: 232ff.). Other good summaries of Jacob, Jed Waldman, William Munger, Michael rain (and other natural) water studies were pre- Hoffmann, Volker Mohnen and others) but also sented by Liebig and Kopp (1853: 705ff., Mole- in Germany (Hans-Walther Georgii, Wolfgang schott (1859: 387ff.) and Ludwig (1862: 1ff.). Jaeschke). The most extensive and so far longest cloud chemistry monitoring programme started in 1992 at Mt. Brocken (Harz, Germany) where more 5.3 Fog and cloud chemistry than 25.000 water samples based on hourly collec- tions have been analysed over the last 15 years In contrast to precipitation chemistry, it was much (Acker et al. 1996). It is planned to continue this pro- more difficult to collect water from fog or clouds, gramme for another 15 years under the name of BRO- primarily because appropriate sampling tech- CLIM, Brocken Cloud Chemistry Climatology. niques (from an analytical point of view), were missing and due to the irregular and infrequent occurrence of fog and the labour-intensive sam- 5.4 From smoke and town fog to smog pling on mountains. The first chemical analyses (urban fog) of fog water were carried out by Boussingault at Liebfrauenberg in Alsace, in Paris and in the Rhine John Evelyn (1620-1706), an educated writer and valley (1853-54). Boussingault found nitrate, be- one of the founders of the Royal Society in Lon- tween 2 mg per l (at the mountain site) and 138 don (1660), wrote the first book on air pollution mg per l (in Paris), and an ammonium concentra- (Evelyn 1661: 8ff.): “… in Clouds of Smoake and tion of 10 mg per l in Paris. Unfortunately, he was Sulphur, so full of Stink and Darkness … It is this only interested in nitrogen, from an agricultural horrid Smoake which obscures our Churches, and 34 Detlev Möller DIE ERDE makes our Palaces look old, which our Clothes, and and smoke”, Marsh wrote that fog was a natural corrupts the Waters, so as the very Rain, and re- phenomenon, whereas smoke, passing through freshing Dew which fall in the several Seasons, fog, could not dissipate like in non-foggy weath- precipitate this impure vapour, which, with its black er because of the absence of air currents, and the and tenacious quality, spots and contaminates “clean natural fog gradually becomes more and whatever is exposed to it. … poysoning the Aer more impregnated with smoke” (this is not correct with so dark and thick a Fog, as I have been hardly because smoke particles act as condensation able to pass through it, for the extraordinary stench nuclei, and thus “clean natural fog” could not and halitus it send forth;… Arsenical vapour, as possibly have appeared in cities like London in well as Sulphur, breathing sometimes from this those years). Smoke and fog as contemporaneous intemperate use of Sea-Coale… our London Fires, phenomena were scientifically described by Ju- there results a great quantity of volatile Salts, which lius Berend Cohen (1859-1935), professor for or- being very sharp and dissipated by the Smoake, ganic chemistry in Leeds who had studied chem- doth infect the Aer, and so incorporate with it, that istry in Munich. He defined: “Town fog is mist the very Bodies of those corrosive particles…” made white by Nature and painted any tint from yellow to black by her children; born of the air of Evelyn’s remark on p. 28 concerns volatile salts particles of pure and transparent water, it is con- and their corrosive effects after distribution in the taminated by man with every imaginable abomi- air and may form the first evidence for gaseous nation. That is town fog” (Cohen 1895: 369). (and, consequently, dissolved) HCl in the urban air. His expression “… traveller … sooner smells Cohen conducted laboratory experiments and than sees the city ...” (Evelyn 1661: 19) gives us concluded: “The more dust particles there are, the an idea on the air pollution level. The terms thicker the fog” (Cohen 1895: 371). Carbonic acid

‘smoake’ and ‘clouds’ in Evelyn’s booklet (only (CO2) and sulphurous acid (SO2) were observed once he uses the term ‘fog’) surely mean what we to increase rapidly during fog, and, “… although now call by the word smog, an artificial expression I have no determinations of soot to record, the fact coined by Harold (Henry) Antoine des Voeux, a that it increases also is sufficiently evident,” he

French physician living in London, honorable wrote. With these terms the acid anhydrides CO2 th treasurer of the Coal Smoke Abatement Society and SO2 were mentioned in the literature of the 19

(formed in 1882) and later President of the National century and not the acids H2CO3 and H2SO3 Smoke Abatement Society (Marsh 1947) in his (sometimes also named gaseous carbonic acid). paper “Fog and Smoke” for a meeting of the Pub- Fog water particles become coated with a film of lic Health Congress in 1905. sooty oil. Consequently, fog persists longer than under clean conditions. Francis Albert Rollo Until the end of the 20th century, when the air pol- Russell (1849-1914), a British meteorologist, used lution problems associated with the combustion the expression “smoky fog” and wrote that “town of fossil fuels seem to have been solved (still un- fogs contain an excess of chlorides and sulphates, solved is the climate change problem due to car- and about double the normal, or more, of organic bon dioxide), sulphur dioxide and soot (smoke) matter and ammonia salts” (Russell 1895: 234). have been the key air pollutants for centuries. Coal During the last fortnight of February 1891, the has been used in cities on a large scale since the weight of the fog deposit in Kew (just outside beginning of the Middle Ages; and this ‘coal era’ London) was 0.84 g per m2 which contained has not ended yet. Remarkably, the term ‘smog’ 42.5 % carbon, 4.8 % hydrocarbons, 4 % sulphu- is not used in Marsh’s book “Smoke” (Marsh ric acid, 0.8 % hydrochloric acid, 1.1 % ammonia, 1947). Concerning the “relationship between fog and 41.5 % mineral matter (Russell 1895). 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 35

The observation that fog sometimes has an during the absence of the sun. John Tyndall odour had been reported much earlier. Lampa- (1823-1893), the Irish physicist known for the first dius, who still considered fog as a suspension explanation of atmospheric heat in terms of the of vesicles which include an electric fluid, wrote: capacities of various gases to absorb or transmit “Die Nebel zeigen zuweilen einen Geruch, der in radiative heat, wrote the following very clear einigen Fällen jenem der brennbaren Luft, in an- phrase: “Aqueous water is always diffused deren aber sich dem Geruch der elektrischen through the atmosphere. The clearest day is not Materie nähert. Diese Erscheinung kann uns exempt from it; indeed, in the Alps, the purest vielleicht auf einen chemischen Prozeß der skies are often the most treacherous, the blue Wasserzerlegung bey genauerer Beobachtung deepening with the amount of aqueous vapour führen, oder vermengen sich bloß aufsteigende in the air. Aqueous vapour is not visible; it is not Gasarten mit dem Nebel? [Fogs at times have an fog; it is not cloud, it is not mist of any kind. These odour which in some cases is approximately that are formed of vapour which has been condensed of inflammable air, in other cases resembles that to water; but the true vapour is an impalpable trans- of electric matter. This phenomenon may lead us parent gas. It is diffused everywhere throughout to a chemical process of water decomposition if the atmosphere, though in very different propor- more precisely observed, or is it possible that this tion” (quoted from Strachan 1866: 123). is only a result of mixing different kinds of as- cending gases with fog?]” (Lampadius 1806: 125). The first statement I found in the literature on the fact that dew contained traces of atmospheric ori- Prout (1834: 315) wrote that “fogs have been gin (and not alchemistic elements) besides water sometimes observed of a strong odour, appar- is given by Lampadius (based on his experiment ently the result of an admixture of foreign bod- of 1796) who said that dew consisted of pure wa- ies”. A special fog or haze, called “dry fog” (in ter and some carbonic acid (2 %) but more than in modern terms: stratospheric aerosol veils) was rain water (Lampadius 1806). He also wrote that described for the years 1782 and 1783 (due to dew may contain substances emitted from plants the Laki eruption in Iceland). (“Ausdünstungsmaterien”) and had therefore been used before as medicine – bleaching proper- ties of dew have been known for centuries – and 6. On Dew for the cleansing of clothes. Textiles had long been whitened by grass bleaching (spreading the cloth William Charles Wells (1757-1817), born in upon the grass for several months), a method vir- South Carolina (USA) as the son of Scottish im- tually monopolised by the Dutch from the time of migrants, became physician, philosopher and the crusades to the 18th century. They developed a printer. He was the first to satisfactorily explain technique in which the cloths were alternately the phenomenon of dew. He went to England in soaked in alkaline solutions and grassed, or croft- 1784 and after most decisive experiments on dew ed – a procedure in which they are exposed to air he published his book “An Essay on Dew and and sunlight; the textiles were then treated with sour Several Appearances Connected with it” in Lon- milk to remove excess alkali. Today, we explain this don in 1814. This was the first scientific descrip- phenomenon by surface photo-catalytic oxidant for- tion of dew formation after a long debate, and mation, i.e. radicals (OH) either via HNO2 formation - even now it is still generally accepted. Wells or by direct O2 electron transfers.). showed that apparently all these phenomena (in- cluding hoar-frost and mist) resulted from the Probably the first chemical study on dew was effects of heat radiation from the earth’s surface conducted by the French chemist Jean-Sébastien- 36 Detlev Möller DIE ERDE

Eugène Julia de Fontenelle (1790-1842) who, in cipitation chemists” – does not only create re- 1819, collected 4 litres of dew in the marshes of spect for our scientific ancestors but may definite- Cercle, France, and found chloride, sodium, po- ly help to avoid many scientifically meaningless tassium, sulphate, calcium and carbonate (Fon- studies of the kind that have appeared over the tenelle 1823) and mentioned: “This water was in- last 20 years. Nevertheless, the history of explor- odorous, without colour, and clean; in a short ing the atmospheric waters is not yet closed and time it deposited small flakes of nitrogenous is likely to remain endless. The endeavour remains matter” (quoted from Pierre 1859: 41, also in to learn from previous studies to ask the appro- Smith 1872: 241). The first quantitative estimates priate open questions and draw the right conclu- of ammonia in dew are known from Boussingault sions for further studies. (1853) taken at Mt. Liebfrauenberg (3-50 mg per l) and from the German agricultural chemists Wolf and Knop, gathered at Möckern near Leipzig in 8. Biographical Notes 1860 (1-6 mg per l). While Boussingault collected dew using a sponge, Wolf and Knop collected Bezold, Wilhelm von (1837-1907) was professor of dew with a glass cup from grass leaves before meteorology in Munich as well as director of the sunrise (Knop 1868, annex: 77f.). Prussian Meteorological Institute. His main interest as a scientist was the physics of the atmosphere and he contributed much to the theory of electrical storms. Renewed interest in dew formation, its physics and chemistry, arose after 1960 because of sev- Boussingault, Jean Baptiste Joseph Dieudonne (1802- eral aspects: first, due to dry deposition on wet- 1887), French agricultural chemist, was the author of Traité d’économie rurale (1844), which was remo- ted surfaces (Chang et al. 1967; Brimblecombe delled as Agronomie, chimie agricole et physiologie and Todd 1977), second, because of ecological (5 vols., 1860-1874; 2nd ed. 1884), translated into considerations in the last two decades (dew as many languages, in German as “Die Landwirthschaft source of moisture for plants, biological crusts, in ihren Beziehungen zur Chemie, Physik und Meteo- insects and small animals, e.g. Jacobs et al. rologie”, Halle 1851, and supplement „Beiträge zur 2000) and its potential use as potable water Agricultur-Chemie und Physiologie” (1856), with (Beysens et al. 2006; Muselli et al. 2006) and fi- ample data on ammonia and nitrate in the air. nally from an air chemical point of view, now also Brandes,Heinrich Wilhelm (1777-1834), professor of termed interfacial chemistry (Rubio et al. 2006, physics at Leipzig since 1826. Founder of synoptic Acker et al. 2007). Beysens (1995) closed the meteorology, published the first weather map in 1820. “historical cycle” to Wells (1814) with his de- Dove, Heinrich Wilhelm (1803-1879), German meteo- scription of dew formation. rologist, founder of comparative climatology. In 1845 he became professor of physics in Berlin, later direc- tor of the Prussian Institute of Meteorology. It was 7. Conclusion Dove’s major contribution to meteorology “to be the first to find a system in weather changes”; he is also Today, an uncountable number of precipitation regarded as the “father of modern meteorology”; president of the “Gesellschaft für Erdkunde zu Ber- chemistry study sites exist, often only active for lin” for several periods between 1848 and 1872. short periods with sometimes barely more than a dozen samples that are collected and analysed for Ferrel, William (1817-1891), American mathemati- cian, teacher and later meteorologist. Among his whatever purpose. The history of atmospheric works published during the last ten years of his life water studies, at least since the systematic moni- were “Popular Essays on the Movements of the th toring in the second half of the 19 century – Atmosphere” (1882), “Temperature of the Atmos- which is certainly unknown to most modern “pre- phere and the Earth’s Surface” (1884), “Recent 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 37

Advances in Meteorology” (1886), and “A Popular Prout, William (1785-1850), spent his life as a Treatise on the Winds” (1889). practising physician in London and occupied him- Hann, Julius von (1839-1921), from 1874 to 1897 self with chemical research in biology and physics. professor of physical geography at the university He is known for his idea that the atomic weight of Vienna; 1897/00 in Graz and again, until 1910, in every element is a multiple of that of hydrogen. Vienna Hellmann, Johann Georg Gustav (1854-1939), pro- fessor of meteorology at Berlin’s Friedrich-Wil- 9. References helms-Universität, 1907-1922 director of the „Preu- ßisches Meteorologisches Institut” (later: German Acker, K., D. Möller, W. Wieprecht and S. Naumann Weather Service); president of the “Gesellschaft für 1996: Mt. Brocken, a Site for a Cloud Chemistry Erdkunde zu Berlin” for several periods between Measurement Programme in Central Europe. – 1901 and 1918 Water, Air and Soil Pollution 85: 1979-1984 Howard, Luke (1772-1864), British manufacturing Acker, K. and D. Möller 2007: Atmospheric Varia- chemist and amateur meteorologist tion of Nitrous Acid at Different Sites in Europe. – Environmental Chemistry 4: 242-255 Helmholtz, Hermann Ludwig Ferdinand von (1821- 1894), professor of physics, anatomy and physio- Acker, K., D. Beysens and D. Möller 2007: Nitrite in logy at Berlin, Königsberg, Bonn and Heidelberg Dew, Fog, Cloud and Rain Water. An Indicator for Heterogeneous Processes on Surfaces. – Atmospheric Knop, Wilhelm (1817-1891), German professor of Research 87: 200-212 agricultural chemistry in Leipzig (1861-1882), suc- cessor to Wolff as director of the agricultural experi- Aitken, J. 1880: On Dust, Fog and Clouds. – Nature mental station (1856-1866). He wrote several books 23: 34-35 on fertilizing and agricultural chemistry. Knop(1868) Aitken, J. 1881: On Dust, Fogs and Clouds. – Transac- mentionsDr. W. Wolf. Most certainly this is not Emil tions of the Royal Society of Edinburgh 30: 337-368 von Wolff (1818-1896), German agricultural chemist, Anon. 1677: Mutus liber, in quo tatem tota Philoso- who was the first director of the (first German) phia Hermetica figuris hieroglyphicis depingitur, agricultural experimental station in Leipzig-Möckern Aurore cujus nomen est Altus 1677 – La Rochelle (1851-1854) and 1854-1894 professor at the Univer- Anon. 1824: Rezension zu Fontenelle, J.-S.-E. de sity of Hohenheim (today a part of the city of Julia de 1823: Recherches historiques, chimiques et Stuttgart), but perhaps one of Knop’s assistants. médicales sur l’air marécageux. – In: Rust, J.N. (Hrsg.): Kopp, Hermann Franz Moritz (1817-1892), Ger- Kritisches Repertorium für die gesamte Heilkunde. man chemist, a student of Liebig’s and later profes- Vol. 3. – Berlin: 138-144 sor in Heidelberg, since 1843; known for his books Anthes, R., H.A. Panofsky, J.J. Cahir and A. Rango on the history of chemistry 1975: The Atmosphere. – Colombo Lamarck, Jean-Baptiste [Pierre Antoine de Monet, Aristoteles 1829: Meteorologica. Ex Recensione Chevalier de] (1744-1829), French biologist and Immanuelis Bekkeri. – Berlin meteorologist Aristoteles 1923: Meteorologica. – In: The Works of Ludwig, Herrmann (1819-1873), German professor Aristotle. Translated by E.W. Webster. – Oxford of analytical chemistry in Jena Aristoteles 1952: Meteorologica. – With an English Margules, Max (1856-1920), Austrian meteorolo- translation by H.D.P. Lee. – The Loeb Classical gist; born in Brody (Ukraine), 1885-1906 member Library 397. – London of the “Zentralanstalt für Meteorologie”, worked especially on tides, established a theory on polar Ashworth, J.R. 1933: Smoke and the Atmosphere. fronts and air pressure waves. Studies from a Factory Town. – Manchester Moleschott, Jakob (1822-1893), Dutch physicist Aßmann, R. 1885: Mikroskopische Beobachtung der and physiologist in Utrecht, Heidelberg and Rome Wolken-Elemente auf dem Brocken. – Meteoro- logische Zeitschrift 2: 41-47 38 Detlev Möller DIE ERDE

Beysens, D. 1995: The Formation of Dew. – Atmos- Cavendish, H. 1766: Three Papers Containing pheric Research 39: 215-237 Experiments on Factitious Air. – Philosophical Beysens, D., C. Ohayon, M. Muselli and O. Clus Transactions 56: 141-184 2006: Chemical and Biological Characteristics of Cavendish, H. 1784: Experiments on Air. – Philoso- Dew and Rain Water in an Urban Coastal Area phical Transactions 74: 119-153 (Bordeaux, France). – Atmospheric Environment Chang, T.Y., G. Kuntasal and W.R. Pierson 1967: 40: 3710-3723 Night-time N2O5/NO3 chemistry and Nitrate in Dew Bergerac, S.C. de 1657: L’autre monde ou les états Water. – Atmospheric Environment 21: 1345-1351 et empires de la lune. – Paris Cohen, J.B. 1895: The Air of Towns. – Annual Bertels, C. 1842: Das Regen- und Schneewasser in Report of the Smithsonian Institution: 349-387 Hinterpommern, chemisch untersucht. – Journal für Coulier, P.J. 1875: Note sur une nouvelle propriété de Praktische Chemie 26 (1): 89-96 l’air. – Journal de Pharmacie et de Chimie 22: 165-173 Beysens, D. 1995: The Formation of Dew. – Atmos- Crosland, M.P. 1962: Historical Studies in the Lan- pheric Research 39 (1): 215-237 guage of Chemistry. – London Bineau, A. 1852: Über die Chemische Zusammen- Deluc, J.-A. 1786: Idées sur la météorologie. – London setzung der Regenwässer, welche im Winter 1851- Deluc, J.-A. 1787: Neue Ideen über die Meteoro- 1852 auf dem Observatorium von Lyon aufgefan- logie. Aus dem Französischen übersetzt von J.H. gen wurden. – Journal für Praktische Chemie 55: Wittekop. – Berlin 476-478 Deluc, J.-A. 1787: New Ideas on Meteorology. Boerhaave, H. 1732: Elementa chemiae: quae anni- Translated from the French. – Berlin, Stettin versario labore docuit, in publicis, privatisque, scholis. – Leyden Descartes, R. 1637: Les Météores. – Reprint: Die Meteore. German translation, edited by C. Zittel. – Boerhaave, H. 1741: A New Method of Chemistry; Frankfurt am Main Including the History, Theory, and Practice of the Art: Translated from the Original Latin of Dr. Dickinson, E. 1686: Epistola ad theodorum munda- Boerhaave’s Elementa Chemiae, as published by num philosophum adeptum. De quintessentia philo- himself, by R. Longman. – London sophorum et de vera physiologia una cum quæstioni- bus aliquot de secreta materia physica. – London Borrichius, O. 1674: Hermetis, Aegyptiorum et chemicorum sapienta ab Hermanni Conringii anim- Diogenes Laertius 1921: Leben und Meinungen adversionibus vindicata. – Copenhagen berühmter Philosophen. Translated and explained by O. Apelt. – Leipzig Boussingault, J.B. 1853: Mémoire sur le dosage de l’ammoniaque contenue dans les eaux. – Annales de Du Fay, C.F. de Cisternay 1736: Mémoire de Paris. – Chimie et de Physique, 3e sér. 39: 257-293 quoted after Gehler’s Physikalisches Wörterbuch. – Leipzig 1839 Boussingault, J.B. 1854: Mémoire sur la quantité d’ammoniaque contenue dans la pluie, la rosée et la Durant, W. 1950: The Age of Faith. A History of brouillard recueillie loin des villes. – Annales de Medieval Civilization, Christian, Islamic and Judaic, Chimie et de Physique, 3e sér. 40: 129-155 from Constantine to Dante: AD 325-1300. – The Story of Civilization 4. – New York Brandes, R. 1826: Beiträge zur Kenntnis der Meteor- wässer. – Neues Journal für Chemie und Physik 48: Egnér, H., E. Eriksson and A. Emanuelson 1949: 153-183 Composition of Atmospheric Precipitation. I. Samp- ling Technique. Use of Ion Exchange Resins. – Brimblecombe, P. and I.J. Todd 1977: Sodium and Annals of the Royal Agricultural College of Sweden Potassium in Dew. – Atmospheric Environment 16: 593-602 11: 649-650 Evelyn, J. 1661: Fumifugium: or, The Inconven- Canseliet, E. 1991: Die Alchemie und ihr Stummes iencie of the Aer and Smoak of London Dissipated. – Buch (Mutus liber). – Amsterdam London. – several reprints 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 39

Flammarion, C. 1873: The Atmosphere. Transla- Wissenschaften, Physikalisch-Mathematische ted from the French. – New York Klasse 1. – Berlin Fontenelle, J.-S.-E. de Julia de 1823: Dissertation Henriet, H. 1897: Les gaz de l’atmosphère. – Ency- sur les eaux minérales connues sous le nom de Bains clopaedias. Encyclopédie scientifique des aide- de Rennes. Recherches historiques, chimiques et mémoire 184B. – Paris médicales sur l’air marécageux. Ouvrage couronné Houghton, H.G. 1955: On the Chemical Composi- par l’Académie des sciences de Lyon. – Paris tion of Fog and Cloud Water. – Journal of Meteoro- Fresenius, C.R. 1846: Anleitung zur quantitativen logy 12: 355-357 chemischen Analyse. – Braunschweig Howard, L. 1803: Essay on the Modification of Gehler, J.S.T. 1825-45: Gehler’s Physikalisches Clouds. – Tilloch’s Philosophical Magazine Vol. 17, Wörterbuch. – Leipzig No. 65. – London Gersten, C.L. 1733: Tentamina systematis novi ad Hube, J.M. 1790: Über die Ausdünstung und ihre mutationes barometri ex natura elateris aerei de- Wirkungen in der Atmosphäre. – Leipzig monstrandas, cui adjecta sub finem Dissertatio roris Jacobs, A.F.G., B.G. Heusinkveld and S.M. Berko- decidui errorem antiquum et vulgarem per observa- wicz 2000: Dew Measurements along a Longitudinal tiones et experimenta nova executiens. – Frankfurt Sand Dune Transect, Negev Desert, Israel. – Inter- Gilbert, O. 1907: Die meteorologischen Theorien national Journal of Biometeorology 43: 184-190 des griechischen Altertums. – Leipzig Kämtz, L.F. 1840: Vorlesungen über Meteorologie. –Halle Girardin, M. 1839: Analyse des grélons. – Journal de Knop, W. 1868: Der Kreislauf des Stoffs. Lehrbuch Pharmacie et des Sciences Accessoires 25: 390-392 der Agricultur-Chemie. – Leipzig Gmelin, L. 1852: Handbuch der Anorganischen Kopp, H. 1843: Geschichte der Chemie: zur Ergän- Chemie. 1. Band. – 5. Auflage. – Heidelberg zung jedes neueren Lehrbuches der Chemie. – Braun- Guericke, O. von 1672a: Experimenta nova (ut schweig. – Reprint Leipzig 1931 vocantur) Magdeburgica de vacuo spatio. – Reprint Kopp, H. 1869: Die Entdeckung der Zusammenset- from the first edition in Latin. – Halle 2002 zung des Wassers. – In: Kopp, H.: Beiträge zur Guericke, O. von 1672b: Neue (sogenannte) Magde- Geschichte der Chemie. – Braunschweig: 235-309 burger Experimente über den leeren Raum. Drittes Kopp. H. 1886: Die Alchemie in älterer und neuerer Buch: Die eigenen Experimente. Deutsche Überset- Zeit. Ein Beitrag zur Kulturgeschichte. – 2 Bände. – zung aus dem Lateinischen von A. Kauffeldt. – Heidelberg. – Reprint Hildesheim und New York 1962 Leipzig 1986 Kratzenstein, C.G. 1744: Abhandlungen von dem Guericke, O. von 1672c: Neue (sogenannte) Magde- Aufsteigen der Dünste und Dämpfe, welche von der burger Versuche über den leeren Raum. – 2. Auflage, Akademie zu Bordeaux den Preis erhalten. – Halle hrsgg. von F. Krafft. – Düsseldorf 1996 Lamarck, J.-B. 1802: De nouvelles observations sur Hall, R.E. 1973: Al-Khazini. – In: Gillispie, C.C. les vents, sur les circonstances propres à la forma- (ed.): Dictionary of Scientific Biography. Vol. 7. – tion des nuages, sur l’ordre de température des New York: 335-351 différentes couches de l’atmosphère, et sur les faits Harting, P. 1854: Skizzen aus der Natur. Aus dem météorologiques que l’on recueille dans divers points Holländischen übersetzt von J.E.A. Martin. – Leipzig de la République et qui sont réunis, comparés, conservés à Paris dans les Bureaux de la statistique Harting, P. 1856: Ueber den Hagel. – Archiv der de France. – In: Lamarck, J.-B.: Annuaire météoro- Pharmazie 6 (135): 30-41 logique pour l’an XI de l’ère de la République Helmont, J.B. van 1652: Ortus medicinae, id est, Française, à l’usage des agriculteurs, des médecins, initia physicae inaudita. – Amsterdam des marins, etc. 4. –Paris Hellmann, G. 1920: Beiträge zur Erfindungs- Lampadius, W.A. 1793: Versuche und Beobachtun- geschichte meteorologischer Instrumente. – gen über Elektrizität und Wärme der Atmosphäre Abhandlungen der Preußischen Akademie der angestellt im Jahre 1792 nebst der Theorie der Luft- 40 Detlev Möller DIE ERDE elektrizität nach den Versuchen des Herrn de Luc und Manget, J.-J. 1702: Bibliotheca chemica curiosa. – einer Abhandlung über das Wasser. – Berlin, Stettin Geneva Lampadius, W.A. 1806: Systematischer Grundriss Marggraf, A.S. 1753: Examen chymique de l’eau. – der Atmosphärologie. – Freiberg Histoire de l’Académie Royale des Sciences et des Lampadius, W.A. 1834: Über die Quellwässer des Belles-Lettres: 131-157 sächsischen Erzgebirges, so wie über die atmosphä- Marggraf, A.S. 1786: Chemische Untersuchung des rischen Wässer. – Journal für Praktische Chemie gemeinen Wassers. – Physikalische und medicini- 1 (1): 100-111, 2 (1): 281-290 sche Abhandlungen der Königlichen Academie der Lampadius, W.A. 1837: Fortgesetzte Beiträge zur Wissenschaften zu Berlin 4: 69-95 Kenntnis verschiedener Wasser. – Journal für Prak- Marsh, A. 1947: Smoke. The Problem of Coal and the tische Chemie 10 (1): 78-88 Atmosphere. – London Lavoisier, A.L. de 1789: Traité élémentaire de Middleton, W.E.K. 1965: A History of the Theories chimie, présenté dans un ordre nouveau et d’après of Rain and Other Forms of Precipitation. London nd les découvertes modernes. – 2 vols. – Paris. – 2 Moleschott, J. 1859: Physiologie der Nahrungs- edition Paris 1793. mittel. Ein Handbuch der Diätetik. – 2. Auflage. – Lavoisier, A.L. de 1790: Elements of Chemistry in a Gießen New Systematic Order Containing All the Modern Möller, D. 2006: Wieviel Chemie ist im Klima? Eine Discoveries. Translated by Robert Kerr. – Edinburgh chemische Klimatologie. – In: Möller, D. (Hrsg.): Lavoisier, A.L. de 1792: System der antiphlogisti- Klimawandel – vom Menschen verursacht? 8. Sym- schen Chemie, 2 vols. Translated by Sigismund posium Mensch – Umwelt. – Acta Academiae Sci- Friedrich Hermbstädt. – Berlin and Stettin entiarum 10. – Erfurt: 106-152 Lawes, J.B., J.H. Gilbert and R. Warington 1882: On Möller, D. and K. Acker 2007: Chlorine-Phase the Amount and Composition of the Rain and Drai- Partitioning at Melpitz near Leipzig. – In: nage Waters Collected at Rothamsted. – Journal of O’Dowd, C. and P. Wagner (eds.): Nucleation and the Royal Agricultural Society of England, 2nd Series Atmospheric Aerosols. Proceedings of the 17th 17: 241-279, 311-350, 18: 1-71 International Conference, Galway, Ireland 2007. – Le Roy, C. 1751: Mémoire sur l’élévation et la Berlin et al.: 654-658 suspension de l’eau dans l’air et sur la rosée. – Mosheim, J.L. von 1726: Institutiones historiae Histoire de l’Academie Royale des Sciences avec les ecclesiasticae Novi Testamenti. – Frankfurt and mémoires de mathématique et de physique: 481-518 Leipzig Le Roy, C. 1771: Mémoire sur l´élévation et la suspen- Mrose, H. 1966: Measurements of pH and Chemical sion de l’eau dans l’air et sur la rosée. – In: Le Roy, C.: Analyses of Rain-, Snow- and Fog-Water. – Tellus Mélanges de physique et de médecine. – Paris: 1-60 18: 266-270 Liebig, J.v. 1835: Über einige Stickstoffverbin- Musschenbroek, P. van 1726: Elementa Physicæ: dungen. – Poggendorfs Annalen der Physik und conscripta in usus academicos. – Leyden Chemie 34: 570-613 Musschenbroek, P. van 1736: Beginselen der Natuur- Liebig, J. und H. Kopp (Hrsg.) 1853: Jahresbericht kunde. – Leyden über die Fortschritte der reinen, pharmaceutischen Musschenbroek, P. van 1739: Essai de physique. – und technischen Chemie, Physik, Mineralogie und 2 vols. – Leyden Geologie. – Gießen: 705-709 Musschenbroek, P. van 1744: Elements of Natural Liebig, J.v. 1865: Die Chemie in ihrer Anwen- Philosophy. Translated from the Dutch by John dung auf Agricultur und Physiologie. 1. Theil. – Colson. – 2 vols. – London 8. Auflage. – Braunschweig Musschenbroek, P. van 1747: Grundlehren der Natur- Ludwig, H. 1862: Die natürlichen Wässer in ihren wissenschaft. Translated from the 3rd Latin edition chemischen Beziehungen zu Luft und Gesteinen. – by Johann Christoph Gottscheden., – Leipzig Erlangen 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 41

Muselli, M., D. Beysens, E. Soyeux and O. Clus Scheele, C.W. 1777: Chemische Abhandlung von der 2006: Is Dew Water Potable? Chemical and Biolo- Luft und dem Feuer. – Ostwald’s Klassiker der gical Analyses of Dew Water in Ajaccio (Corsica exakten Wissenschaften 58. – Leipzig 1894 Island, France). – Journal of Environmental Quality Scheele, C.W. 1908: Discovery of Oxygen. Part 2. – 35 (5): 1812-1817 Alembic Club Reprints 8. – Edinburgh Newton, I. 1704: Opticks or A Treatise of the Schneider-Carius, K. 1955: Wetterkunde – Wetter- Reflexions, Refractions, Inflections and Colours forschung. Geschichte ihrer Probleme und Erkennt- of Light. Also Two Treatises of the Species and nisse in Dokumenten aus drei Jahrtausenden. – Orbis Magnitude of Curvilinear Figures. – London academicus 2, Naturwissenschaftliche Abteilung 9. – Okita, T. 1968: Concentration of Sulfate and Other Freiburg Inorganic Materials in Fog and Cloudwater and in Sigg, L. und W. Stumm 1996: Aquatische Chemie. Aerosol. – Journal of the Meteorological Society of Eine Einführung in die Chemie wässriger Lösungen Japan 46: 120-127 und natürlicher Gewässer. – 4. Auflage. – Stuttgart Petrenchuk, O.P. and V.M. Drozdova 1966: On the Smith, R.A. 1852: On the Air and Rain of Man- Chemical Composition of Cloud Water. Tellus chester. – Memoirs of the Literary and Philosophical 18: 280-286 Society of Manchester 10: 207-217 Pierre, J.I. 1859: Chimie Agricole ou l’agriculture Smith, R.A. 1872: Air and Rain. The Beginnings of a considéreé dans ses rapports principaux avec la Chemical Climatology. – London chimie. – 10e edition. – Paris Stark [no initials available] 1814: On Rain Water. – Philalethes, I. 1667: Introitus apertus ad occlusum Annals of Philosophy 3: 140-142 regis palatium. – Hamburg Stöckhardt, J.A. 1871: Untersuchungen über die Philalethes, I. 1673: Chymisches Zwey-Blat, das schädliche Einwirkung des Hütten- und Steinkohlen- ist Zwey vortreffliche Chymische Tractätlein. Das rauches auf das Wachstum der Pflanzen, insbesondere erste, eröffneter Eingang zu deß Königs verschlos- der Fichte und Tanne. – Tharandter Forstliches senem Pallaste. – Frankfurt und Hamburg Jahrbuch 21: 218-254 Pott, J.H. 1753: Lithogéognosie ou examen chymique Strachan, R. 1866: Appendix to the Reprinted Edi- des pierres et des terres en general et du talc, de la topaze tion of Wells, W.C. 1814: An Essay on Dew and et de la stéatite en particulier, avec une dissertation sur Several Appearances Connected with it. – London le feu et sur la lumière, traduit de l’Allemand. – Paris Stumm, W. (ed.) 1990: Aquatic Chemical Kinetics. Priestley, J. 1775: The Discovery of Oxygen. Part Reaction Rates of Processes in Natural Waters. – I. Experiments. – Alembic Club Reprints 7. – Re- New York print Edinburgh 1947 Stumm, W. and J. Morgan 1996: Aquatic Chemistry: Prout, W. 1834: Chemistry, Meteorology and the Chemical Equilibria and Rates in Natural Waters. – Function of Digestion with Reference to Natural 3rd edition. – New York Theology. – 2nd edition. – London Szabadváry, F. 1966: History of Analytical Che- Rubio, M.A., M.J. Guerrero, V. Guillermo and E. mistry. – Oxford Lissi 2006: Hydroperoxides in Dew Water in Tomlinson, C. 1847: The Dew-Drop and the Mist; Downtown Santiago, Chile. A Comparison with Or, an Account of the Nature, Properties, Dangers, Gas-Phase Values. – Atmospheric Environment and Uses of Dew and Mist, in various parts of the 40 (32): 6165-6172 world. – London Russell, F.A.R. 1895: The Atmosphere in Relation Torstensson, G. 1954: Stickstoff- und Schwefelver- to Human Life and Health. – In: Annual Report of bindungen aus der Atmosphäre und ihre Bedeutung the Smithsonian Institution. – Washington D.C.: für die Pflanzen. – Sitzungsberichte der Deutschen 203-348 Akademie der Landwirtschaftswissenschaften Saussure, H.B. de 1783: Essais sur l’hygrométrie. – 3 (18): 18 Neuchâtel 42 Detlev Möller DIE ERDE

Umlauft, F. 1891: Das Luftmeer: die Grundzüge der processes were not understood before the 19th cen- Meteorologie und Klimatologie nach den neuesten tury. The key in understanding the transformation Forschungen gemeinfasslich dargestellt. – Wien et al. of water through its different states (solid, liquid and Vogel[no initials available] 1828: Das Pyrrhin scheint gaseous) was the comprehension of the role of the keine eigenthümliche Substanz zu sein. – Archiv für heat exchange during evaporation and condensation. die gesammte Naturlehre 15: 97-101 This understanding grew parallel to the understan- ding of the combustion process as a chemical reac- Vogel, A. 1883: Zur Geschichte der Liebig’schen tion using atmospheric oxygen. This happened Mineraltheorie. – Sammlung gemeinverständlicher between 1770 and 1790, with Deluc providing the wissenschaftlicher Vorträge, Serie 18, Heft 426. – best comprehensive description in 1787. Together Berlin with the understanding of the heat exchange associa- Waite, A.E. 1887: The Real History of the Rosicru- ted with phase transformation, the role of radiation cians. Founded on Their Own Manifestoes, and on (direct solar versus terrestrial) was considered, too. Facts and Documents Collected from the Writings of Dew formation was first described correctly by Initiated Brethren. – London Wells (1814). However, microphysical cloud dro- Walden, P. 1941: Geschichte der organischen Chemie plet reflection was only explained a hundred years seit 1880. – Berlin later with the finding that water may condense in the Waller, A. 1847: Microscopic Observations on the atmosphere only on condensation particles (Ait- So-Called Vesicular Vapours of Water, as Existing in ken), and with Aßmann closing the long debate of the Vapours of Steam, and in Clouds, &c. – In: droplets versus vesicles. Cloud dynamic processes Philosophical Transactions of the Royal Society of and rain formation, however, were not generally London 137: 23-30 understood before the 1920s; measurement plat- forms (balloons and aircrafts) become a precondition Warington, R.A.1889: The Amount of Nitric Acid in in improving (and validating) cloud and rain theories the Rain-Water at Rothamsted, with Notes on the based on mathematical descriptions. Cloud physics Analysis of Rain-Water. – Journal of the Chemical as a subdiscipline did not start before 1960. At the Society, Transactions 55: 537-545 beginning, the driving force for a better physical Wells, W.C. 1814: An Essay on Dew and Several description of the phenomena of atmospheric waters Appearances Connected with it. – London. – Reprint was pure philosophic interest to understand nature; edited by R. Strachan. – London 1866 later, practical purposes became more important Wigand, A. 1913: Über die Natur der Kondensations- with meteorological monitoring for weather forecas- kerne in der Atmosphäre, insbesondere über die ting and climatology. Chemistry of atmospheric waters Kernwirkung von Staub und Rauch. – Meteorologi- started in the Middle Ages with the alchemistic sche Zeitschrift 30: 10-18 attempt to transmute water coming from the atmo- Zimmermann, W. 1824: Beiträge zur näheren Kennt- sphere (“heaven”). On the other hand, already at that th nis der wässrigen Meteore. – Archiv für die gesamm- time (in the mid-17 century), fog and rain (and likely te Naturlehre 1 (3): 257-292 dew) were considered to be polluted in towns but also regarded as cleansing agents. The first semi-quantita- tive chemical analysis of rain and snow was conduc- ted by Marggraf in Berlin around 1750, with the purpose to consider the hygienic quality of potential Summary: On the History of the Scientific Explora- drinking-water. More detailed rain water analyses tion of Fog, Dew, Rain and Other Atmospheric Water were performed at the beginning of the 19th century for the same reasons and in combination with the In this paper the milestones in exploring clouds, fog, application of newly developed methods in analyti- rain and dew in physics and chemistry from Anti- cal chemistry. Liebig’s theory of plant nutrition from quity until the end of the 20th century have been air promoted a rapidly increasing number of chemical described. While a good description of the phenome- studies of rain and fog. Since then, agricultural inte- nology had been available since Aristotle, the actual rests form an important base for rain water chemistry 2008/1-2 History of the Exploration of Fog, Dew, Rain and Other Atmospheric Water 43 monitoring. Air pollution in urban areas but also physik als eine Teildisziplin entwickelte sich aber forest damages (in Germany) stimulated several stu- nicht vor 1960. Die treibende Kraft zu einer besseren dies at the end of the 19th century. Deposition studies physikalischen Beschreibung des Atmosphärenwas- (bulk sampling) due to the smoke problem started sers war zunächst reines philosophisches Interesse after 1910. The aim to understand matter cycles, first am Verständnis der Natur. Erst mit den beginnenden between local and regional scales, initiated precipita- meteorologischen Aufzeichnungen für Wettervor- tion chemistry in the 1930s which led to systematic hersage und Klimatologie nahmen praktische Erwä- research since the 1950s. gungen an Bedeutung zu. Die Chemie des Atmosphä- renwassers begann im Mittelalter mit alchemisti- schen Versuchen der Transmutation (Umwandlung) von Wasser, welches aus der Atmosphäre („dem Zusammenfassung: Zur Geschichte der wissen- Himmel“) stammte. Andererseits hatte man bereits schaftlichen Erforschung von Nebel, Tau, Regen in dieser Zeit (der Mitte des 17. Jahrhunderts) Nebel und anderem Atmosphärenwasser und Regen (und wahrscheinlich auch Tau) sowohl als verschmutzt als auch als reinigende Agenzien in Dieser Artikel beschreibt die wichtigsten Etappen Städten beschrieben. Eine erste halbquantitative in der Erkundung von Wolken, Nebel, Regen und chemische Analyse von Regen und Schnee wurde Tau von der Antike bis zum Ende des 20. Jahrhun- durch Marggraf um 1750 in Berlin durchgeführt, mit dert. Während die Phänomenologie des Atmosphä- dem Ziel einer hygienischen Bewertung als Quelle renwassers bereits seit Aristoteles gut beschrieben für Trinkwasser. Mit Beginn des 19. Jahrhunderts wurde, verstand man die Prozesse erst im 19. Jahr- wurden genauere und umfangreichere Regenwasser- hundert. Das Verständnis über die Phasenumwand- analysen, aus hygienischen Gründen aber auch der lung des Wassers (in seiner flüssigen, gasförmigen Anwendung der sich entwickelnden neuen analyti- und festen Form) wurde erst möglich, nachdem die schen Methoden, durchgeführt. Liebigs Theorie der Rolle des Wärmeaustauschs während des Verdamp- Pflanzendüngung aus der Luft führte zu einer zuneh- fens und Kondensierens klar wurde. Zwischen 1770 menden Anzahl chemischer Untersuchungen von und 1790, als Deluc im Jahr 1787 die bis dahin Regen und Nebel. Das landwirtschaftliche Interesse klarste Theorie vorstellte, wuchs dieses Verständ- blieb seit dieser Zeit eine wichtige Grundlage für nis zeitgleich mit dem Verstehen des Verbrennungs- niederschlagschemische Messreihen. Die Luftver- prozesses als chemischer Reaktion unter Bindung schmutzung in Städten, aber auch Waldschäden in von Luftsauerstoff. Zugleich wurde mit dem Ver- Deutschland initiierten zahlreiche Untersuchungen ständnis des Wärmeaustausches im Zusammenhang zum Ende des 19. Jahrhunderts. Wegen der Rauch- mit dem Phasenübergang auch die solare Strahlung frage begannen nach 1910 Depositionsuntersuchun- (sowohl die direkte als auch die terrestrische) be- gen (bulk-Probenahme). Mit dem Ziel, Stoffkreis- trachtet. Die Taubildung wurde erstmals 1814 durch läufe zuerst zwischen lokaler und regionaler Ebene Wells korrekt beschrieben. Eine mikrophysikali- zu verstehen, wurde die Niederschlagschemie in den sche Beschreibung der Wolkentropfen wurde je- 1930er Jahren etabliert, was in den 1950er Jahren zu doch erst 100 Jahre später möglich, nach der Er- systematischer Forschung führte. kenntnis, dass Wasser in der Atmosphäre nur an Kondensationskernen (Aitken) kondensieren kann. Auch wurde die lang anhaltende Diskussion, ob es sich um Tropfen oder Bläschen handelt, durch Aß- Résumé: Sur l’histoire de la recherche scientifique mann beendet. Die dynamischen Prozesse in Wol- du brouillard, de la rosée, de la pluie et des autres ken und die Regenbildung wurden jedoch prinzipiell eaux atmosphériques erst in den 1920er Jahren verstanden, wobei Mess- plattformen (Ballons und Flugzeuge) eine Voraus- Le présent article décrit les étapes les plus importan- setzung für die Verbesserung (und Verifizierung) tes dans l’exploration de nuages, brouillard, pluie et von auf mathematischen Modellen basierenden rosée de l’Antiquité jusqu’au XXe siècle. Alors que Wolken- und Regentheorien bildeten. Die Wolken- la phénoménologie de l’eau atmosphérique était déjà 44 Detlev Möller DIE ERDE bien décrite à l’Antiquité, les processus n’ont été à cette époque-là (au milieu du XVIIe siècle) on avait compris qu’au XIXe siècle. La compréhension du déjà décrit le brouillard et la pluie (et, probablement, changement de phases de l’eau (dans son état liquide, également la rosée) comme agent à la fois sale et gazeux et solide) n’était pas possible avant que le purifiant dans les villes. Une première analyse chi- rôle du transfert de chaleur pendant l’évaporation et mique semi-quantitative de pluie et de neige a été la condensation soit devenu clair. Cette compréhen- réalisé par Marggraf en 1750 à Berlin et avait comme sion augmentait dans la période de 1770 à 1790 lors but l’évaluation hygiénique de l’eau potable. Des que l’on comprenait de plus en plus le processus de analyses plus importantes et plus précises de l’eau la combustion en tant que réaction chimique sous pluviale ont été réalisées dès le début du XIXe siècle, utilisation d’oxygène, quand, en 1787, Deluc en a non seulement pour des raisons hygiéniques, mais présenté la théorie la plus claire. En même temps, aussi pour l’application des nouvelles méthodes lors de la combinaison du transfert de chaleur et le analytiques en voie de développement. La théorie de changement de phase, on avait également pris en Liebig sur la nutrition de plantes par l’air a engendré considération le rayonnement solaire (direct et ter- un nombre croissant d’analyses chimiques de la pluie restre). La première description correcte sur la for- et du brouillard. L’intérêt agricole est désormais une mation de rosée, par Wells, date de l’année 1814. des bases les plus importantes pour des séries de Cependant, la description microphysique des gout- mesure en chimie de précipitation. La pollution de tes de nuages n’a été réalisée que 100 ans plus tard, l’air dans les villes ainsi que le dépérissement des après que l’on avait découvert que l’eau dans l’at- forêts en Allemagne ont entraîné de nombreuses mosphère ne peu condenser qu’avec des noyaux de recherches vers la fin du XIXe siècle. À cause du condensation (Aitken). C’était Aßmann qui termi- problème de la fumée, on a commencé des recherches nait finalement la longue discussion sur s’il s’agit de de déposition (bulk sampling) après l’année 1910. gouttes ou de vésicules. Pourtant, les processus Dans le but de comprendre les circuits de matière, dynamiques dans les nuages et la formation de la d’abord entre l’échelle locale et régionale, la chimie pluie n’ont été compris que dans les années 1920. des précipitations s’est établie dans les années 1930 Avec ça, les plateformes de mesure (des ballons et et est systématiquement analysée depuis 1950. des avions) sont devenues indispensables pour l’amélioration (et la vérification) des théories de nuages et de pluie basées sur des modèles mathéma- tiques. Or, la physique des nuages en tant que Prof. Dr. Detlev Möller, Atmospheric Chemistry discipline ne se développait pas avant 1960. Au and Air Pollution Control, Faculty of Environmental début, la force vive d’une meilleure description des Sciences and Process Engineering, Brandenburg eaux atmosphériques était l’intérêt purement philo- Technical University, P.O. Box 10 13 44, 03013 sophique à comprendre la nature, les aspects prati- Cottbus, [email protected] ques n’ont gagné de l’importance qu’avec les enre- gistrements météorologiques pour les prévisions du temps et la climatologie. La chimie des eaux atmos- phériques est née au Moyen Age avec des essais alchimiques de la transmutation (transformation) Manuskripteingang: 10.01.2008 d’eau de l’atmosphère (« du ciel »). De l’autre coté, Annahme zum Druck: 28.05.2008