s FEBRUARY 111113

February 1993

Aspirin 4 Acetylsalicylic acid has been the mainstay of the home medicine cabinet for generations, but its mode of action is not yet fully understood. Ink 8 You’re looking at it now without seeing it. The printing on this page is really a complex mixture of chemicals. Car Cooler 11 When your car has been parked in the sun and it’s hotter than an oven, the “pssst” of this spray can bring relief. MysteryMatters 12 Saint’s Blood 12 The solid, dried blood has liquefied many times during the last 500 years. Is it a miracle or the work of a clever medieval chemist? The Puzzle Page 16 Chemistry Rhyme Time ASPIRIN

By Gail Marsella Scene Three. The year is 1992. A and are some of the oldest and most high school student, diligently study­ frequently used drugs. Willow trees Scene One. The year is 1614; the ing for an exam, develops a contain salicin, oil of wintergreen is place is eastern Massachusetts. Four headache after several hours of methyl salicylate, and aspirin is members of the Wampanoag tribe of intense concentration. She goes to acetylsalicylic acid (see Figure 1). American Indians have developed the medicine cabinet, takes out a bot­ high fevers. The shaman ventures out tle marked "aspirin ," and swallows Painful discoveries into the forest, where he carefully col­ two pills with a glass of water. In less At some time in the remote past, a lects some leaves, roots, and bark than an hour, her headache is gone. primitive physician may have tried from a willow tree. He returns home, Taking medicine to relieve pain, using the bark from a willow tree to grinds up the plant material, and fever, and inflammation is a ritual that relieve a patient's pain or fever. brews it in water. The patients drink has been repeated through most of Unlike so many other plant remedies the hot herbal tea, and bathe in a recorded history. Willow tree bark that were tried, this one worked! cooled solution of the ground bark. extract, oil of wintergreen, and aspirin Many cultures have a history of Within hours, the fevers are lower, are similar in molecular structure and herbal medicine, so the same discov­ and the sick people are resting com­ metabolic effect. All three belong to a ery was probably made hundreds of fortably. group of chemicals called sa/icy/ates, times, beginning with very early Scene Two. The year is 1846; the humans. place is London, England. On the day These first investigations were of the Prince's annual ball, the Grand mostly "trial and error" (much to the Duchess is suffering from severe joint dismay of the suffering patient). pain due to arthritis. She sends for Studying the actual chemistry of med­ her doctor, and is given oil of winter­ icinal plants began only in the 1800s. green to swallow. In a short time the Imagine the difficulties the early inflammation in her joints lessens, chemists faced! Identifying the active and she can move without pain. The ingredient in a mound of willow tree duchess attends the ball, and fulfills bark was a formidable task. From the her social obligations. hundreds of chemicals contained in , 11-- _ ./-1 °II C ~.t n '-OCH3 '( by Dr. Hoffman nearly a century ago. \J-OH Win~~~;:een l~ When acetylsalicylic acid ages, it may decompose and return to salicylic Methyl Salicylate ..--... S.\!1 acid and acetic acid. If you have a '\.--- _ 'V If' very old bottle of aspirin around the /HYd'OIYS;S \\y~7?I; house, open it and take a sniff. It may /~/ smell like vinegar, because vinegar is ~/)\----\ ~I/ \~/ dilute acetic acid. ~{I ~\ J ~. \~~~~~~~r0~c) )j/~---- Something for everyone \ \', \\ Researchers have been puzzled by ~1\\ \ ~" \\.~ ..4P! \ the many and varied actions of ~ /' 1 1'\\.' '\ ~/- lJ \ -..... I aspirin. This one drug not only il. \ 1\\ \, Salicylic Acid // ,""- l • ,{ I \' \ IY I l \ I " ",

f \\ ° Ii \ V \\ A' . O-C-CH3 splnn g

Acetylsalicylic Acid

Figure 1. Salicylates have been used as painkillers since ancient times. Salicin can be extracted from the bark of willow trees, and methyl salicylate is found in winter­ Take a"BAVER~ BREAK"! green plants, also called teaberry. Aspirin was first prepared by the acetylation of salicylic acid, which results from heating a solution of salicylic acid and acetic acid in the presence of sulfuric acid. the bark, it was nearly impossible to In 1899, a German scientist named purify the single chemical capable of Felix Hoffman suggested acetylsali­ relieving pain and fever, especially cylic acid as a good alternative to sal­ when the chemist was working with­ icylic acid. He had been searching for out the computers and analytical a drug that would give his elderly equipment we routinely use today. father relief from severe arthritis, and In the mid-1800s the German he stumbled upon acetylsalicylic acid chemist Hermann Kolbe synthetized after trying phenyl salicylate and sodi­ salicylic acid (so named because the um salicy1ate without success. The scientific name for willow is Salix) in new drug was named aspirin-a from his laboratory by heating phenol with acetyl, and spirin from spiraea (mead­ carbon dioxide. Although several dif­ owsweet flower), one of the natural ferent plants are able to relieve fever plant sources of salicylic acid. Hoff­ and pain, the active chemical part of man worked at the Bayer Company, all of them is salicylic acid. Unfortu­ which marketed the new remedy with 1Take 2 Bayer Aspirin for your headache. 2 Sit down and relax. nately, salicylic acid is very irritating great success. Aspirin became a With Bayer Aspirin and afew minutes' rest, you'll feel fine in practically no time. Try it. to the stomach-so much so that mainstay of the home medicine cabi­ 3 -makeWh" 'h'youho,feel."'h,,tense, "dheadachy,h;gh h,m;d;',all worn g,tout,'"justdo.,stop I a~take I many patients preferred their aches net; today, Americans swallow nearly for a few minute.s a "Bayer Break"! Thanks to :. -! Instant flaking action, Bayer brings the fastest, gentlest 'relief you can set from hot·weather aches and pains,;; •-- and fever to the severe heartburn 50 million tablets a day. N"";m.y",,,'''h,,'bo,t,''',k,'''.''''.''''.'' We promiseyou'Jlfeel betterfastl ill caused by the remedy. So the search Aspirin can be made easily in the was on for a chemical that was simi­ laboratory by reacting acetic acid with This aspirin advertisement from 1961 lar to salicylic acid-but without the salicylic acid to produce acetylsali­ looks out of date, but modern ads side-effects. cylic acid, the same procedure used promote the same benefits.

CHEM MATTERS, FEBRUARY 1993 5 relieves fever, pain, and inflamma­ tion, but also inhibits blood clotting. Which of these people should be cautious about taking aspirin for their pain-the boy with sore muscles or the girl with the flu? Some new evidence indicates that it may help prevent some types of heart attacks if taken regularly. None of these effects seems to be very close­ ly related. Despite its many years of use, aspirin's mode of action is only partly understood. Unlike many painkillers (such as narcotics) that act directly on the ner­ vous system, aspirin seems to relieve pain primarily by stopping the produc­ tion of hormone-like chemical mes­ sengers called prostaglandins. Hormones are messengers that are produced in one part of the body and act on another. Prostaglandins, in contrast, are produced by the same tissue as the one they act upon. They are produced in very tiny amounts and are degraded within a few min­ utes, but in their short lifetime they exert a powerful influence on the body. Prostaglandins regulate diges­ tion, kidney output, reproduction, blood circulation, and some nervous system functions. Aspirin interferes with the action of one particular enzyme, cyclooxyge­ nase, which acts at the beginning of a chain of prostaglandin synthesis. As a result, all the prostaglandins pro­ duced by this chain of reactions are suppressed. All of aspirin's numerous effects-reducing fever, enlarging blood vessels, reducing clotting of the Reye's syndrome is a rare, potentially fatal illness that can strike people blood-eome from altering the bal­ who have used aspirin to treat symptoms of a viral infection, such as flu or ance of prostaglandins, even though chicken pox. No age group is immune, but Reye's syndrome most com­ aspirin itself disturbs only a single monly strikes young people from infants to age 19. Early symptoms include reaction. severe vomiting and drowsiness; later symptoms may include confusion, irrational behavior, delirium, convulsions, and coma. There is no cure for Too much of a good thing Reye's syndrome, but early treatment can improve the chances of recov­ If a person takes an overdose of ery. The disease affects all organs of the body but especially the liver aspirin, the salicylic acid absorbed by (where it causes accumulation of fat) and the brain (where it increases the stomach and intestine lowers the pressure). Exactly how aspirin interacts with the viral infection is still pH of the blood. The body responds unclear. by breathing more rapidly to get rid of Since 1986, all aspirin labels carry the warning, "Children and teenagers some carbon dioxide, in an attempt to should not use this medicine for chicken pox or flu symptoms before a doc­ reduce the blood acidity. Then the tor is consulted about Reye's syndrome, a rare but serious illness." Read kidneys start to work overtime to labels carefully; confusion can arise when the product is not called aspirin, excrete the excess acid from the but contains aspirin as one of its ingredients (such as Alka-Seltzer, Anacin, blood, and the person may become Ecotrin). dehydrated. If the dose of aspirin is In 1991,57% of people diagnosed with Reye's syndrome died, though extremely large, the body cannot the fatality rate was only 10% when the disease was diagnosed early. compensate, and the extra acid in the M.O. blood starts to damage the brain,

6 CHEM MATTERS. FEBRUARY 1993 patients, the drug companies intro­ liver, and other tissues. This o acid-base imbalance is called acido­ duced specially coated aspirin tablets II sis, and is potentially fatal. (See box, that pass through the stomach with­ H" /C" Acidosis, in "Mystery Matters, Poi­ out dissolving. The coating resists the soned Milk," in the December 1992 acid juices of the stomach, but dis­ I CH, issue of Chern Matters.) solves quickly in the basic environ­ : What should you do if you find ment of the small intestine. Called your little brother or sister has swal­ "enteric" aspirin, these tablets effec­ Acetaminophen lowed a lot of aspirin? Or eaten a tively eliminate stomach irritation, but ¢ (Tylenol) whole tube of Ben-Gay, which con­ they cannot work until the contents of OH tains methyl salicylate? First-and the stomach are passed to the intes­ most important-call your local poi­ tine, which may not happen until sev­ o son control center and ask for instruc­ eral hours after the tablet is ingested. CH 3 II \C tions (the telephone operator will give People who need a constant dose C/ "OH you the number). Salicylate poisoning of analgesic, or who are treating H ~\H causes ringing in the ears, extremely symptoms of flu or other viral illness, H \~ rapid breathing, nausea, and, surpris­ frequently turn to the aspirin-free \ /C ingly, fever. Once these symptoms alternatives. The most common is /C \ Ibuprofen appear, the situation is very serious, CH "cH (Advil, Motrin) 3 3 and the patient needs medical treat­ ment immediately. Simulated stomach

You can see the difference acetaminophen, marketed under the Stomach upset between regular aspirin, buffered "Over-the-counter" drugs do not familiar name "Tylenol" as well as aspirin, and enteric aspirin by test­ other brands. Like aspirin, aceta­ require a doctor's prescription-but ing the tablets in neutral, acidic, that doesn't mean they're not potent minophen reduces fever and relieves and basic solutions. Your stomach pain, but it has no effect on inflamma­ medicines. Aspirin is a very effective is acidic, but your small intestine is painkiller and fever reducer, but it tion or blood clotting. Ibuprofen (sold basic. These chemical opposites under the brand names Motrin and causes side-effects in some people. are separated by the pyloric valve, Most common is the problem of stom­ Advil) is another non-aspirin which opens only briefly to transfer painkiller. ach upset. Though aspirin is much partially digested food from the less irritating than plain salicylic acid, The discovery that aspirin works stomach to the intestine. by inhibiting prostaglandin opened it causes stomach upset in a very Begin with three transparent small percentage of people. One new avenues of medical research. A glasses or plastic cups. Add 120 specific prostaglandin that promotes strategy for reducing stomach irrita­ mL (1/2 cup) of water to each con­ tion coagulation of the blood and another is to combine the aspirin with an tainer. Note the time, then simulta­ acid buffer-a combination of chemi­ that inhibits coagulation have been neously add a regular aspirin identified. A new group of cals that reduces acidity. The result­ tablet to one container, a buffered ing product, buffered aspirin, is a prostaglandins was discovered by fol­ aspirin to another, and an enteric genuine help for this group of people. lowing the clue that aspirin reduces aspirin tablet to the third. Note most forms of inflammation but not However, the drug manufacturers changes in the tablets at 30-sec­ used buffers as a way to distinguish the inflammation of asthma. ond intervals until no further Researchers have learned a lot from their brand of aspirin from others and change is evident. To simulate the produced a blitz of TV advertisements the once-mysterious ingredient of the acid environment of the stomach, bark of the willow tree. claiming, "Our aspirin won't upset repeat this procedure using vine­ your stomach." The claim is both cor­ gar in each container instead of Gail Marsella is a chemist and freelance rect and misleading. Buffered aspirin water. You will see one of the science writer living in Allentown. PA. is a genuine improvement for the tablets dissolve more vigorously small percentage of people who are References than before. To simulate the basic Maheady, Donna Carol. "Reye's Syndrome: susceptible to this kind of stomach intestine, repeat once more, using Review and Update"; Journal of PediatriC irritation, but it has no value to the a solution made by adding 16.3 g Health Care; September-October, 1989 Vol. rest of us. 3, NO.5. (1.5 teaspoons) of powdered bak­ Roueche, Berton. The Medical Detectives; For people who are under a doc­ ing soda, NaHC03, to the 120 mL Chapter 5, "Aspirin"; Times Books: New tor's orders to take aspirin around the of water. One of the tablets will York. clock every day (arthritis sufferers, for Willis, Judith Levine. "On the Teen Scene: dissolve suddenly after a delay of Using Over-the-Counter Medications Wise­ example), stomach irritation can 20-30 minutes. D.P.R. ly"; FDA Consumer Magazine, November become a serious issue. For these 1991.

CHEM MATTERS, FEBRUARY 1993 7 INK

By Judy K. Miller

Look around you and see whether you can spot any ink. In addition to the ink-printed words you are reading now, you may see more printing ink on a news­ paper or poster. If you've been writing in a notebook, Some pigments are inor­ you'll see some ballpoint ganic (contain no carbon), pen ink. And what about that such as titanium dioxide blue-lined paper? Those (white), lead chromate (yel- lines were printed with ink. If low), cadmium selenide (red), you're having a snack, take a and ferric ferrocyanide (blue). close look at that soda can and potato chip bag. Both Vehicles have. been printed with ink. The vehicle has a tough job. It Then there's the calendar on must be a liquid so it can flow the wall and the wallpaper. from the pen or printing press Even some brands of toilet onto the substrate, and then, to tissue are decorated with ink­ hold the pigment in place, it printed designs. must thicken to a near-solid The Egyptians used inks condition-instantly. In addition, it 4000 years ago to write official doc­ must disperse the pigment but not uments. Their writing products were AARON LEVIN dissolve it. This impossible list of primitive, but they contained the requirements has kept ink chemists essential components: a pigment, a diameter. If the coloring agent were in busy for decades. vehicle, and a substrate. The sub­ solution, it would soak into the sub­ There are four ways to make the strate is the surface that is printed strate with the vehicle, and the print­ vehicle change quickly: evaporation, upon and could be paper, parchment, ing might show through on the back absorption, oxidation, and polymer­ or a Pepsi can. The Egyptians used side of the paper. Because the pig­ ization. The Egyptians used a water papyrus-a coarse paper-like materi­ ments are dispersions, the large parti­ solution of plant gums as the vehicle. al made from a plant of the same cles are deposited on the surface. name. For a pigment or coloring More than half the ink used in the agent, the Egyptians used carbon United States is black, and most of soot. The vehicle is the liquid that car­ the black pigment is made-like the ries the pigment from the pen to the Egyptian ink-of elemental carbon. substrate, then hardens to hold it The carbon may come from burning there. The Egyptians used a mixture hydrocarbon fuels such as oil or nat­ of water and plant gum. ural gas, or from organic waste such as wood, vines, or bones. In every Pigments case, carbon-containing compounds Without pigments there would be are reduced to elemental carbon such nothing to read-no letters on the as soot or lamp black. The end prod­ substrate. Because the vehicle is a uct contains only carbon but, depend­ liquid, it is logical to assume that the ing on the source, the particles vary pigment is dissolved in the vehicle, in size and light absorption. but it is not. The pigment is a finely Carbon also appears in colored ground insoluble solid that is dis­ pigments, but it appears here not as persed in the vehicle. If it were dis­ an element but as part of organic Figure 1. This copper-based blue pig­ solved, it would consist of separate molecules (carbon is one of the ele­ ment is called phthalocyanine blue. molecules. Instead, each particle con­ ments in the molecule). An example The ink industry is continually trying to synthesize new pigments that will give tains millions of molecules and is typi­ of a blue pigment is shown in more realistic images when used in cally 0.00001 mm to 0.0005 mm in Figure 1. combination with other colors.

8 CHEM MAnERS, FEBRUARY 1993 After the ink was applied to the sub­ strate, the water evaporated, which caused the gum to harden. Water­ based inks are still used; you have probably complained about them when they were slow to dry on a humid day or streaked when the writ­ ing got wet. To overcome the disadvantages of water-based inks, ink makers turned to oils; linseed oil became the vehicle of choice. Because oils are hydropho­ bic, they will not dissolve in water and the ink will not run if it gets wet. Made by squeezing oil from flax seeds, lin­ seed oil is a mixture of oleic acid, linoleic acid, and linolenic acid (see Figure 2). Linseed oil solidifies by oxi­ dation when it is exposed to air. The oxygen in the air causes linoleic and linolenic acids to polymerize-join to form much larger molecules. Ink mak­ ers call linseed oil a "drying oil" because it can solidify. Another drying oil is tung oil, also known as chinawood oil. Tung oil is This small laboratory press is used to test batches of printing inks. Most printing primarily made up of the glycerides today is done by offset lithography, which exploits the fact that water and oil don't mix. The printing cylinder is made of aluminum, which is hydrophilic-easily wet (fat-like molecules) of eleostearic by water. In areas that will be printed, such as text or photos, the aluminum is acid. The molecules in linseed oil coated with a hydrophobic polymer that repels water but is easily coated with the have two double bonds, but oil-based ink. As the cylinder rotates, it comes into contact with water-coated eleostearic acid has three (Figure 3). rollers (not shown) and then ink-coated rollers, seen above. The alternate arrangement (double The water coats the bare aluminum areas but not the polymer areas; the ink coats the polymer areas but not the wet aluminum. The cylinder transfers the ink bond, single bond, double bond) to a second rubber-covered cylinder, which transfers it to the paper. Because the makes tung oil oxidize and polymer­ letters are reversed when transferred to the rubber cylinder, and reversed again ize more readily, hence its superior when transferred to the paper, the letters read correctly on the original cylinder. performance as a drying oil. The words you are now reading were printed by offset lithography. Some drying oils still don't harden fast enough to meet the demands of modern printing presses. To speed , ./'-.... ./'-.... ./'-.... ./C.:::::-./'-.... ./'-.... ./'-.... ./'-.... ".. 0 ~ ~ ~ ~ C' ~ ~ ~ ~C".. things up, the linoleate salts of cobalt, I lead, or manganese are added. Oleic acid OH These salts act as catalysts by carry­ ing oxygen to the oil molecules.

Solvent pollution In the past, organic solvents were often added to oil-based inks to make them more fluid. The solvents made the ink less viscous while it was being applied to the substrate, then made it more viscous when the solvents were absorbed into the substrate or evapo­ rated into the air. The solvents gave a Figure 2. Linseed oil contains a mixture of these fatty acids. The presence of dou­ characteristic smell to the printer's ble bonds makes them more reactive to oxygen in the air.

CHEM MATTERS, FEBRUARY 1993 9 shop as well as the pages of a freshly printed document. Typical organic solvents were low molecular weight alcohols such as methyl alcohol, ethyl alcohol, or isopropyl alcohol; glycols Eleostearic acid such as ethylene and propylene; ketones such as acetone; and hydro­ Figure 3. Tung oil, comprised largely of eleostearic acid, above, is often added to printing ink. Because it has three double bonds, it readily polymerizes to form a carbons such as hexane, heptane, solid. Tung oil is also applied to furniture to give a hard, smooth finish. toluene, and xylene. But when these solvents evaporate, they add to our air pollution. The Federal Clean Air Act of 1970 dictates that such volatile compounds be limited to no more than 20% of the weight of the ink unless the printer installs equipment that traps and recovers the solvent vapors. The organic solvents have been replaced by special plasticizers. In anticipation of more stringent pollution requirements, some ink Figure 4. Natural oils have largely been replaced by tougher, faster drying synthet­ makers are returning to water-based ics such as this alkyd resin. When dry, the ink would contain thousands of such inks. The new formulations contain as linked structures. much as 65% water but are not com­ pletely free of organic solvents. Alco­ more porous the substrate, the faster are very large molecules made up of hols and glycols are used to help the drying by absorption; the warmer repeating parts. Resins originally dissolve the resin and to lower the the environment, the more effective came from natural sources such as water's surface tension. the evaporation. Printers sometimes pine trees and the like. Since the Absorption and evaporation are use heat to help dry the printed ink. early 1900s, however, synthetic affected by the nature of the sub­ Today, ink vehicles are mainly (man-made) resins have been used strate and the drying conditions. The resins, which are polymers. Polymers in ink because of their superior gloss, scuff resistance, and good adhesion to the substrate. An alkyd resin that is Flap test commonly used in ink vehicles might be made up of many repetitions of Modern printing presses are so fast that the ink must be adjusted without this structure (Figure 4). Polymeriza­ stopping the press. While a continuous roll of paper flies through at up to tion, known in the ink industry as 30 miles per hour, a strobe light, flashing many times a second, freezes heat-bodying, causes the resin to the printed image-makes it look as if it is not moving. This allows the thicken and eventually harden. operator to examine the four-color test strip and adjust the flow of each There are four industrial processes color ink on the fly. for printing, and each process If you disassemble a cereal box or cookie box, you may find a series of requires its own inks. In addition, the small rectangles printed in different colors. This is a test strip, which helps ink industry is working to reduce air the printer control each ink in the four-color printing process. Most printers pollution and improve color accuracy. use subtractive inks that absorb the primary colors. On the test strip you It's no wonder that about 1 million will see yellow, which absorbs blue light; magenta (pinkish-red), which new ink formulas are introduced each absorbs green; cyan year. (blue-green), which absorbs red; and Judy Miller teaches English at Virginia black, which absorbs Hollis Community College and is the all colors. Combina­ co-founder of the Appalachian Center for Poets and Writers. tions of these inks are printed as References neighboring dots of The Kline Guide to the Ink Industry; Rauch, J., varying sizes; they Ed.; Charles H. Kline; Fairfield, NJ, 1981. offer control of the Printing Ink Handbook. National Association of Printing Ink Manufacturers; Hasbrouck entire spectrum. Heights, NJ, 1958. American Ink Maker, October 1986, pp. 13-21.

10 CHEM MAHERS, FEBRUARY 1993 CAR COOLER

You've spent a fun day at the beach examples of this phenomenon. If you compressed nitrogen gas or a hydro­ and return to your car to drive home. go jogging on a warm day, the evapo­ carbon gas. Tan received a patent for You open the door, jump in and ... ration of your sweat keeps you from Instant Car Kooler in 1989 and began WHAM! The heat hits you like a fist. overheating. Jog through a lawn marketing it in 16-ounce spray cans. It's 55°C (130 OF) in there! sprinkler and YOU'll get more cooling Want to keep your car cool with Should you open all the windows from evaporation. Still too hot? Rub­ some simple chemistry? You can get and wait ten minutes? Fire up the bing alcohol into your skin is more two 16-ounce cans of Instant Car engine, turn on the air conditioner, effective because, compared to the Kooler by sending a check for $10.98 and retreat to the beach while the car water, alcohol evaporates faster. to General Innovations, 6184A Fran­ cools off? Not if you have a can of The inspiration for the Instant Car conia Road, Alexandria, VA 22310. Instant Car Kooler™ . You can simply Kooler came several years ago when Phone: (703) 719-0202. DP.R. pop the top off the can, spray the physicist Domingo K. L. Tan listened interior of the car for a minute, then to his 12-year-old son's repeated Reference Tan, D.K.L. U.S. Patent 4,813,238, March hop in and drive away. The spray objections to climbing into a broiling 21,1989. makes the interior temperature plum­ hot car. Tan thought about how a met from 55°C to 25 °C (77 OF) in brief rain shower can cool a steaming The water-alcohol solution in Instant seconds. hot afternoon, and decided to use Car Kooler won't boil below 86°C (187 What's in that spray can? Water water droplets to cool his car. With OF); nevertheless, it evaporates very and ethyl alcohol. The water-alcohol the right nozzle, "the drops of spray quickly at 55°C (130 OF). Liquids evap­ orate only from the surface and, com­ solution leaves the can as tiny are so fine," says Tan, "that they pared to the amount of liquid they droplets that quickly evaporate in the vaporize right away." To accelerate contain, the tiny droplets have a very hot air. Whenever a liquid evapo­ the cooling, Tan added ethyl alcohol large surface area; this speeds the rates, its molecules absorb the heat because it is very volatile-it evapo­ transition from droplets of liqUid (A, of vaporization from the surroundings. rates quickly. below) to Individual molecules of vapor (8). To put it another way, when mole­ When one gram of water evapo­ cules evaporate they cool the sur­ rates at 55°C, it absorbs 2360 joules rnllnrllinrlC:: You've seen other of heat from the air. The evaporation of one gram of ethyl alcohol absorbs about 850 joules. Instant Car Kooler contains 10% alcohol (by weight), 90% water, and just a touch of a flo­ ral-mint fragrance. (The water and ethyl alcohol mix readily because both are polar compounds.) The can contains no CFCs; it is pressurized by

8

CHEM MAnERS, FEBRUARY 1993 11 MYSTERY MATTERS

In Naples, Italy, a bishop tips an ornate reliquary that contains a glass case. Inside are two glass vials of a yellow-brown sub­ stance said to be the 1600-year-old blood of Saint Januarius.

Saint's Blood saint's head. To check whether lique­ methods, a medieval alchemist could By Robin Meadows faction has occurred-which can take easily have created imitation blood from two minutes to more than two that would solidify when undisturbed On Saint Januarius's three feast hours-the priest periodically turns and liquefy when moved. days, what is alleged to be his cen­ the vial of blood upside down. When turies-old blood tranforms from a it flows, he announces, "The miracle Thrown to the bears dark, clotted mass into a liquid. St. has happened," and the crowd The history of St. Januarius's blood is Januarius is the patron saint of chants. sketchy. Although little is known of Naples, and the miracle of liquefac­ Some observers believe that there the saint's life, legend has it that in tion draws thousands of Roman can be no natural explanation for the the year 305 AD he and four other Catholics to the Naples Cathedral to liquefaction of the blood, and it is truly Christians were condemned to be see a priest perform the rite. While a miracle. However, a number of sci­ thrown to the bears by the Romans, the worshippers pray, shouting and entists throughout history have sug­ who had outlawed Christianity. But invoking St. Januarius to liquefy his gested more worldly causes for the when the bears were put in the blood, the priest holds the vial of holy phenomenon. Recently, a team of amphitheater, they refused to touch blood close to an altar bearing what is Italian chemists simulated the lique­ St. Januarius and his companions. So believed to be the remains of the faction in the laboratory. Using their the Romans decapitated the martyrs

12 CHEM MAnERS, FEBRUARY 1993 CATHOLIC BOOK PUBLISHING COMPANY instead. A serving woman named Eusebia collected St. Januarius's blood from the stone on which he had been beheaded, and gave the holy blood to the Bishop of Naples. The blood is kept in an ornate reli­ quary (receptacle for sacred remains) topped by a crown and a cross. The reliquary encloses two airtight vials that contain the blood. One is narrow and contains only a few drops, and the other measures 10 centimeters and is about two-thirds full of a dark mass. The reliquary is stored in a glass case in a guarded vault and is removed only for veneration onSt. Januarius's feast days: the Saturday before the first Sunday in May, which is the feast of moving his remains to Naples; September 19, which is the feast of his martyrdom; and Decem­ ber 16, which is the feast honoring him as the patron saint of Naples. Historical records of the liquefac­ tion extend back many years, and there are at least 37 independent accounts of the phenomenon between 1389 and 1659. Prior to that time, however, the phenomenon is not well documented. The first written notation of the liq­ uefaction miracle was not recorded until 1389, more than 1000 years after St. Januarius's death. The 1389 record is in the diary of an anony­ mous citizen of Naples, who wrote, "...there was a great procession to mark the miracle wrought by our divine Lord with the blood of St. Janu­ arius. The blood, which is kept in a vial, turned into liquid just as if it had been in the living body of Januarius on that very day." Critics have drawn attention to two inconsistencies in the history of the vial of blood. First, one would expect a miraculous object to have a well­ documented history, not to burst onto the scene in the 1300s. Second, the blood has liquefied at least seven An artist's depiction of Saint Januarius, emphasizing the miraculous claims about his blood. Using artistic license to put different parts of the story into one image, times while jewelers were repairing the artist shows Saint Januarius holding what appear to be two vials of his own the reliquary. blood. Volcanic Mount Vesuvius, in the background, may have been the source of These anomalies can be resolved the mineral molysite that could have been used to prepare imitation blood.

CHEM MATTERS, FEBRUARY 1993 13 by the Italian chemists' explanation of the phenomenon. Luigi Garlaschelli, an organic chemist at the University of Pavia, and Franco Ramaccini and Sergio Della Sala, two colleagues in Milan, noticed that the relic behaved like a thixotropic gel. Such gels can liquefy when picked up, shaken, or otherwise disturbed mechanically, and then resolidify when left to stand. Examples of thixotropic gels include some types of mayonnaise, which can be liquefied instantly by shaking or stirring, and toothpaste, which oozes when squeezed from the tube yet does not drip off the toothbrush. Chemists Sergio Della Sala, Franco Ramaccini, and Luigi Garlaschelli cooperated The simple act of inverting the reli­ on the laboratory investigation of simulated blood. They were unable to examine quary containing St. Januarius's the sample that is alleged to be the blood of Saint Januarius, but they prepared an blood would be enough to liquefy iron-based gel that seems to have the same physical properties. some thixotropic gels. Garlaschelli traveled to Naples to to four days. blood were readily available to witness the ceremony and said that Just as salts flow out of the dialysis medieval alchemists living in the the vial of blood "is very dark-maybe membrane, water flows in and so vicinity of Naples. Two of the com­ darker than our gel. It looks more like increases the volume of the iron(lIl) pounds were widely available in the strong coffee than like blood, and it hydroxide solution. To concentrate 1300s: calcium carbonate was doesn't show any red hue and leaves the solution, the chemists put it in a obtained from a variety of sources, on the walls of the bottle a thin yel­ crystallization dish until about half the including chalk (limestone) or finely low-brown layer." His observation of water had evaporated. Finally, they crushed eggshells, and sodium chlo­ the color is significant because added sodium chloride, NaCI, which ride was obtained from rock salt or blood-at least fresh blood-leaves a resulted in a dark, brownish thixotrop­ sea salt. distinctly scarlet color on the walls of ic gel that set in about an hour. The The only source of the third com­ a glass container. gel was easily liquefied by gentle pound, iron(llI) chloride, during that Garlaschelli and his colleagues shaking. The liquefied iron(llI) hydrox­ time was a mineral called molysite, simulated St. Januarius's blood, first ide gel left a thin, yellow-brown layer which occurs naturally only near by dissolving iron(llI) chloride, FeCI3, on the walls of the glass container­ active volcanoes; molysite precipi­ and calcium carbonate, CaC03, in similar to what Garlaschelli observed tates out of lava when hydrochloric distilled water. The two salts reacted when the blood of St. Januarius was acid comes into contact with iron-con­ to form red-brown iron(lIl) hydroxide, liquefied in Naples. taining rocks. Interestingly, Naples is Fe(OHh The next step was purifying near Mount Vesuvius, a 1190-meter the iron(lIl) hydroxide solution by Medieval reagents active volcano. Moreover, after S1. removing the unreacted iron(lIl) chlo­ Most of the techniques used by the Januarius's blood miraculously lique­ ride and the calcium chloride, CaCI2, Italian chemists-using a balance, fied in the 1300s, a number of similar a reaction byproduct. distillation, and crystallization-were miracles occurred in or around The chemists removed these salts known in the 1300s. Dialysis, how­ Naples. by dialysis, which entails putting the ever, is not documented as having These geographical and temporal solution inside a membrane sac with been known until the early 1600s, coincidences suggest that a medieval pores that let small compounds when it was shown that salt could alchemist may have concocted what (such as the salts) out while keeping pass through a bladder. But dyes is believed to be S1. Januarius's larger compounds (such as the were stored in bladders and gut bags blood. Many medieval priests were iron(llI) hydroxide) in. The membrane in the 1300s, and it is entirely possi­ also gifted alchemists. Unfortunately sac is then put in distilled water, and ble that an alchemist living then could for them, in 1317 Pope John XXII for­ the salts flow out through the mem­ have discovered dialysis. Garlaschelli bade the study of alchemy, saying, brane until the concentrations inside and his colleagues showed that their "Alchemists deceive us and promise and outside the sac are equal. The technique works when gut is used for what they cannot perform ... if any chemists changed the distilled water the dialysis bag. members of the clergy are found daily until it no longer turned yellow Likewise, the three compounds among alchemists they will receive no from iron(lIl) ion, which took three used to simulate St. Januarius's mercy."

14 CHEM MAnERS, FEBRUARY 1993 Make a blood-like thixotropic mixture This restriction might have led to In 15.0 mL of distilled water, dissolve 15.0 g of iron(III) chloride hexahy­ the following scenario: Excited by his drate, FeCI306H20. The compound dissolves to form ions, discovery of the thixotropic properties 3 FeCI306H20(s) --+ Fe +(aq) + 3CI-(aq) + 6H20(I) of molysite mixed with chalk, and 3 denied any other way of sharing his and the Fe + ion reacts with water to form a yellow, acidic solution 3 excitement, a priest/alchemist may Fe +(aq) + H20(I) --+ FeOH2+(aq) + W(aq) have presented his finding as St. Jan­ This is the first of a series of three reversible (equilibrium) steps in which uarius's blood on one of the three Fe3+can react with water. Slowly add 4.0 g of powdered calcium carbon­ feast days. As Garlaschelli and his ate, CaC03, while stirring. The mixture will foam from the production of colleagues point out, even if this sce­ CO2gas as some of the acid is neutralized. nario is correct, modern priests who 2 CaC03(s) + 2W(aq) --+ CO2(g) + Ca +(aq) + H20(I) perform the rite of liquefying St. Janu­ arius's blood are not cheating when This reaction consumes Wand therefore causes the FeOH2+ in the sec­ they invert the reliquary; this is the ond reaction to react further with water (in two additional reactions, sum­ only way they can ascertain whether marized in one equation below). The dark brown product consists of very the miracle has occurred. small (colloidal) particles of Fe(OHlJ, FeOH2+(aq) + 2H20(I) --+ Fe(OHh(s) + 2W(aq) Closed vials...open questions Pour some of the solution into a small bottle with a screw-on top, add a The chemists' simulation does not tiny amount (200 crystals) of table salt, NaCI, cap and shake the bottle. disprove the claim that St. Januar­ Let the bottle stand for 24 hours, then tilt it gently to see if it has gelled. If it ius's blood has liquefied, and it cer­ has not, add more salt and repeat the test after 24 hours. If it appears tainly does not prove that the vial solid try shaking it to see if it will liquefy. If it won't, open the bottle, add 10 contains a gel made from iron(III) drops of water, shake, and repeat the test after 24 hours. chloride and calcium carbonate. This chemical system lends itself to many experiments. You may wish Indeed, other researchers have sug­ to divide your sample into two equal portions before adding the salt, keep gested that the vial could contain real one as a control, and add salt (half the amount specified above) to the blood mixed with a thixotropic honey other. It is possible to compare the gel obtained from laboratory-grade cal­ such as that from heather, a shrub cium carbonate with the gel formed when you substitute a medieval with small pinkish flowers. However, source of the compound-finely ground egg shells. Garlaschelli's work shows that neither The gel produced by this formulation is not especially stable and may blood nor a miracle is necessary for precipitate after a few days. Detailed instructions for using dialysis to making a dark brown solid liquefy on make a stable blood-like gel are in the current issue of the Chem Matters command. Classroom Guide. D.P.R. The mystery of the composition of St. Januarius's blood will probably never be solved, because the Catholic Church will not allow analysis of the substance in the vial. However, as Garlaschelli and his colleagues wrote in a report of their work, "Our replica­ tion of the phenomenon seems to render this sacrifice unnecessary."

References Epstein, Michael. "Better Blood through Chem­ istry"; National Capital Area Skeptical Eye: Spring 1992; Vol. 6, No 2. Epstein, Michael; Garlaschelli, Luigi. "Science Investigates Miracles"; Journal of Scientific Exploration 1992; Vol. 6, No 3. Garlaschelli, L.; Rammaccini, F.; Della Sala, S. "Working Bloody Miracles"; Nature: October 10, 1991; Vol. 353, p. 507. Science News, October 12, 1991; Vol. 140, No. 15, p. 229. Thurston, Herbert; Attwater, Donald. Butler's Lives of the Saints; P.J. Kennedy and Sons: New York, 1956; Vol. 3, pp. 594-96.

Robin Meadows is a freelance science writer living in Fairfield, GA.

CHEM MATTERS, FEBRUARY 1993 15 PUZZLE

Chemistry Rhyme Time 11 . The amount of matter in a By Dorothy Mann Lamb substance with an indefinite shape Chicago State University and volume GM Each answer below is two words that rhyme or almost rhyme. The first letter of each word is given; the number of letters in the word is equal to the number of spaces. The first one is done for you, as an example. Answers can be found on page 3.

1. Conversation in the laboratory Lab Gab 6. A very dull, but proven, hypothesis o T

7. Contamination of a homogeneous mixture s p

8. Volumetric glassware that was washed, but not dried WB

9. When acid is added, so that the original substance is neutralized Incessant B E talking about something that has mass and occupies space MC 10. A very famous substance 13. An argument about the composed of two or more elements speed of a chemical reaction 3. Great joy over finding the correct c _ R 0 formulas for a chemical reaction E E

4. An instrument that gives accurate, reproducible results