Sir William Crookes

396 SCIENTIFIC AMERICAN April 19, 1919 Sir William Crookes

An Appreciation of a Great Physicist and Chemist

By John W. N. Sullivan WITH the death of Sir William Crookes, which the rainbow, and in rubies glowing with a rich full red. 'Yet all these were, when no man did them know, took place on April 4th, the world of science Crookes considered the kathode rays to be matter Yet have from wi�est ages hidden been; mourns the loss of an investigator who belonged to a type in a fourth state, neither solid, liquid, nor gaseous. He And later times things more unknowne shall show, which is very seldom met with in modern times. Nowa regarded them as constituted of particles negatively Why then should witlesse man so much misweene days specialization is so intense that it is hard to find a charged and projected with great velocity from the That nothing is but that which he hath seen?"" physicist who has done work in more than one or two negative el�ctrode. It is pleasant to think that Sir William lived long branches of physics, or a chemist who has done work in In essentials this is thG modern view of the rays enough to see his predictions verified and to get a fuller more than one or two branches of chemistry; but in Sir except that while Sir William regarded the negatively view of that mysterious and attractive region which lies William Crookes we had a man who was a direct descen charged particles to have molecular dimensions, they are just over the border. dant from the giants of old; men who could turn their now kno�wn to be very much smaller than the smallest Crookes next, in 188 1, published a research in which he attention with equal ease to several of the great divisions known atom. With real prophetic insight Crookes saw of science, and achieve work of lasting importance in the part that these high vacua phenomena would play returns to considerations connected with the dynamical each. Sir William was born in 1832 and his life is one in the advance of science, and in view of the fact that theory of gases. Maxwell had made the great theoretical long record of scientific research. In 1861 he achieved his these phenomena underlie the whole of modern physics discovery that the viscosity of a gas is independent of the first great scientific discovery, the discovery of the new and have entirely changed our conceptions of the material density, and it had already been the starting point for metal, thallium. He was led to this discovery in a universe, it is of the greatest interest to read the following experimental observations by Maxwell himself, Kundt course of analysis of 10 pounds of the and Warburg, using the method of ro seleniferous deposit from the sulphuric acid tating disks. Crookes took up the subject manufactory at Tilkerode, in the Hartz and devised a very simple yet efficient Mountains, the substance being placed orm of apparatus. He merely suspended at his disposal by Prof. Hofmann in the a larrlina within a bulb containing the year 1850. Spectroscopic examination re gas and noticed the subsidence of its oscil vealed a bright green line which he had lations when it was set vibrating. He found, never met with before, and which he found what Maxwell had himself foreseen, that to be characteristic of a new metal. Dur Maxwell's law completely breaks. down ing the next 12 years researches on the for very high exhaustions. many properties of the new element were In the same year Crookes published a carried out, culminating in his determina paper on an entirely new method of spec tion of the atomic weight. The amount trum analysis, based on the fact that under of labor involved was immense and the the influence of kathode rays a large num care with which the investigation was ber of substances emit phosphorescent carried out was such that even now light. The phosphorescent light from Crookes' value for the atomic weight of most bodies has a continuous spectrum, thallium is regarded as the best. With the but in some cases the spectrum is discon now accepted values for the atomic weights tinuous, and Crookes made a special study of oxygen and nitrogen the atomic weight of such bodies. These experiments com of thallium, as determined by Crookes, is prise his well known researches on the rare 204.04. earths, especially yttria in some of its In making this determination Crookes compounds, and in this connection he ob was troubled by irregularities in the weigh tained very valuable results, to which he ings and, as so often happens in scientific made intermittent additions as time went work, was led to a new discovery, by in on, including the discovery a few years ago, vestigating these apparent errors. The of a new earth, characterized by an isolated weighings were made in a partial vacuum, strong group of lines high up in the ultra but the action of the balance ifl these violet, ascribed by Sir William to a new conditions appeared most capricious. The element named by him victorium. weight of the substance appeared to vary In more recent times he did some valu with the temperature, but not always in the able experimental work on radium. Th� same direction. As a result of his persis substance known as uranium X was first tent efforts to trace the cause of these dis separated from uranium by Crookes in concerting phenomena he was led to invent 1900, by two distinct chemical methods. the well-known' instrument, the radio His well known and popular instrument, meter. The-dynamical theory of gases at the spinthariscope, was the outcome of his once furnished an explanation of the discovery in 1903 that the alpha rays from curio�s effects observed, in terms of the radium produce, by their bombardment, action of the residual gas left over in the phosphorescence on a target of crystalline vacuum; and in spite of the immense zinc Slllphide. amount of work on the stresses in rarefied He married in 1856, when only 24 years gases resulting from inequalities in temper- - of age. He was a member of numerous ature, to which Crookes' discovery gave scientific societies both in England and birth, the subject is not yet exhau.lted. abroad, and among numerous other honors Crookes was thus led to consIder the received the Copley Medal in 1904. He 1897 phenomena which take place in high vacua, was knighted by Queen Victoria in and in his subsequent researches we have and achieved the greatest honor open to an the v<:ry flower of his work. It is well English man of science by being elected known that if we pass an electric discharge president of the Royal Society in 1913. through a high vacuum, rays are shot out His striking combination of diverse from the negative electrode, the kathode, gifts, keen observation, patient and in called kathode rays. They had been in exhaustible experimental skill, together vestigated before Sir William published with the glowing mind and imagination his experiments in 1879, by Glucker in Sir William Crookes of a poet, have assured him for all time a 1859, by Hittorf in 1869, and by Goldstein settled place in the great list of English in 1876, but Crookes, in a series of brilliant experiments, words of Crookes when he alone among his contempor- men of sCIence. aries foresaw the present development in physics: greatly extended our knowledge of their properties and Italian Lavas as a Source of Potash propounded the theory as to their constitution which, "In studying this fourth state of matter, we seem at in a refined form, is the one that is accepted at the length to have within our grasp and obedient to our DR. Henry S. Washington, of the Carnegie Geophysi 'present day. control the little indivisible particles which, with good cal Laboratory, has published a computation of the Jile showed that the kathode rays proceed in a straight warrant, are supposed to constitute the physical basis total amount of potash present in the lavas of the six line from the negative electrode wherever the positive of the universe. We have seen that in some of its chief volcanoes along the west coast of Italy that have electrode may be: that they cast a shadow when inter properties radiant matter is is material as this table, erupted leucitic lavas. A conservative estimate is 10,000,000,000 cepted by solid matter and that they exert a strong while in other properties it almost assumes the character tons of potash (K20). Dr. Washington mechanical action where they strike. He showed that of radiant energy. We have actually touched the border believes that in these volcanoes Italy possesses one of they are .influenced by a magnetic field, the direction of land where matter and force seem tv merge into one t�e largest visible supplies of potash known to exist, if � shadowy realm h Iween o' n %\ - :�ot �he large:ot. Im� tant silicate-rock sources of motion being changed; and that heat is produced when another" .\ql � a ..;,\p . . ?� . . . their motion is arrested. He alsQ conducted some beau known, .whlCh for me has alway,s had peculiar tempta- ;SpotaSh are also a:yallabte�!p. the Umted States, mcludmg :. I tiful experiments on the power of the kathode rays tions. I venture to think tha�: the greatest scientiM'..;. &:t':ij� , Leucite Hills ,in W14$.ing,and the belt of glauconite NewJ�rsey·into to excite phosphorescence in preparations of calcium problems of the future will find their solution in this �hat' extends from Virginia. The latter is 2,034,000,000 sulfide shining with blue-violet, yellow, orange or green border land, and even beyond; here, it seems to me, lie estiinated by Dr. Washington to contain light, in diamonds shining with nearly all the colors of ultimate realities, subtle, far-reaching, wonderful. metric tons of potash.