414 



jVA TURE 



[t"Ei;KUARY 3, 1910 



subjects as education, the position of women, on art and 

 science, and probably on national government. We can 

 hardly guess what would be the influence on such a nature 

 of a rigid administrative regime which forbids even the 

 discussion of such questions. We in England are almost 

 unable to imagine such a state of things as would be 

 represented by the closing of, say, University College for 

 a year or more, because the question whether the House 

 of Lords ought to be abolished had been debated in the 

 Students' Union. Imagine the professor of chemistry, 

 along with his colleagues, for such a reason deprived of 

 the use of his laboratory by the police, and only allowed 

 to resume his studies when someone down at' Scotland 

 Yard thought proper. Such being the experience of most' 

 of the Russian universities and technical high schools it 

 ]s not surprising that the output of Russian science, not- 

 withstanding the acknowledged genius of the Russian 

 people, appears sometimes comparatively small. The 

 amount of work done by Mendeleeff, both experimental and 

 theoretical, was prodigious, and all the more remarkable 

 considermg the cloudv atmosphere under which so much of 

 It was accomplished.' 



In 1882 the Royal Society conferred on MendeMeff 

 jomtly with Lothar Meyer, the Daw medal. In 18S3 the 

 Chemical Society elected' him an honorary member, and in 

 1889 it conferred upon him the highest distinction in its 

 power to award, namclv, the Faraday lectureship with 

 which is associated the Faraday medal'. In 1890 he was 

 elected a Foreign Member of 'the Royal Society, and in 

 1905 he received the Coplev medal. So far as England is 

 concerned, his services to science received full acknowledg- 

 ment. It js all the more remarkable, therefore, that he 

 never became a member of the Imperial Academy of 

 Sciences of St. Petersburg. 



Towards the end of iqo6 Mendel^eff's health began to 

 fail. Nevertheless he was able to attend the Minister on 

 the occasion of an official visit in January to the office of 

 Weights and Measures, but he caught cold and, enfeebled 

 as he had been by influenza in the preceding autumn, in- 

 flammation of the lungs set in. Retaining consciousness 

 almost to the last, he requested even on the day of his 

 death to be read to from the " Journey to the North Pole " 

 by his favourite author, Jules Verne. ' He died in the early 

 morning of January 20 (O.S.), 1907, within a few days of 

 his seventy-third birthday. He was buried in the Wolkowo 

 Cemetery beside the graves of his mother and son. 



Turning now to a survey of Mendel^eflf's work as a man 

 of science, it will be sufficient if we pass lightly over his 

 first essays. Like so many other chemists, he" began by 

 handling simple questions of fact, his first paper, dated 

 1S54, when he was twenty years of age, being on the 

 composition of certain specimens of orthite. It was not 

 until 1859 that he settled down to serious examination of 

 the physical properties of liquids, which led him to a long 

 series of experiments on the thermal dilatation of liquids, 

 of which the chief ultimate outcome was the establish- 

 ment of a simple expression for the expansion of liquids 

 between o and the boiling point. This formula is liable 

 to the same kind of modification which has been found 

 necessary in the case of gases. It is. of course, applicable 

 only to an ideal liquid from which .all known liquids differ 

 by reason of differences of chemical constitution and con- 

 sequent differences of density, viscosity, and other 

 properties. 



Mendeleeff devoted a large amount of time and of ex- 

 perimental skill to the estimation of the densities of various 

 solutions, especially mixtures of alcohol and water and of 

 sulphuric acid and water, and of aqueous solutions of a 

 large number of salts. In i8Sq he embodied the whole in 

 the monograph already referred to. In a paper com- 

 municated to the Transactions in 18S7 (li., 779), he stated 

 his views in the following words: — "Solution's mav be 

 regarded as strictly definite atomic chemical combinations 

 at tetriperatures higher than their dissociation temperatures. 

 Definite chemical substances may be either formed or de- 



1 Prof. Walden, at the tiiH of a bio<rraphical no'ice recently published in the 

 Benclite d. Deut. Chcm. Ges., April, looo, gives a list of 262 printed pub- 

 lications by Meneelecff. These include, not only memoirs on physical and 

 chemical subjects, but hooks, pamphlets, reports, and newspaper articles 

 relatine to exhibitions, to the industries of Russia, to weights and measures, 

 to education, to art. and even to spiritualism. 



NO. 2IOI, VOL. 82] 



composed at temperatures which are higher than those at 

 which dissociation commences ; the same phenomenon 

 occurs in solutions ; at ordinary temperatures they can be 

 either formed or decomposed." These views, however, 

 did not prevent his recognising van 't Hoff's gas theory 

 as applicable to dilute solutions. 



In conjunction with some of his students, Mendeleeff 

 also studied minutely the question of the elasticity of gases, 

 and published several papers on the subject (see Royal 

 Society Catalogue), extending over a period of some ten 

 years from 1872. 



Another subject to which MendeWeff gave a good deal 

 of attention was the nature and origin of petroleum. 

 Having already reported in 1866 on the naphtha springs 

 in the Caucasus, in the summer of 1876 he crossed the 

 Atlantic and surveyed the oil fields of Pennsylvania. In 

 the course of these investigations, he was led to form a 

 new theory of the mode of production of these natural 

 deposits. The assumption that the oil is a product of the 

 decomposition of organic remains he rejects on a variety 

 of grounds, which are set forth in a communication to the 

 Russian Chemical Society (Abstract, see Ber. , 1S77, .x., 

 229). Mendeleeff assumes, as others have done, that the 

 interior of the earth consists largely of carbides of metals, 

 especially iron, and that hydrocarbons result from the 

 penetration of water into contact with these compounds, 

 metallic oxide being formed simultaneously. The hydro- 

 carbons are supposed to be driven in vapour from the 

 lower strata, where temperature is high, to more superficial 

 strata, where they condense and are retained under 

 pressure. In 1886, in consequence of rumours as to the 

 possible exhaustion of the Russian oil fields, he was sent 

 by the Government to Baku to collect information, and in 

 1889 he made a communication on this subject to Dr. 

 Ludwig Mond, which is printed in the Journal of the 

 Society of Chemical Industry (1889, viii., 753). 



The influence of the great generalisation known as the 

 periodic law can best be estimated by reviewing the state 

 of knowledge and opinion before the announcement and 

 acceptance of the principle by the chemical world, and 

 subsequently glancing at the influence which, directly or 

 indirectly, it has produced on scientific thought, not only 

 in regard to the great problems to which it immediately 

 relates, but to the whole range of chemical theory. 



The use of the expression " atomic weight " implies the 

 adoption of some form of atomic theory ; but forty or more 

 years ago Dalton's atomic theory was by many of the most j 

 philosophical chemists and physicists regarded as only a 

 convenient hypothesis, which might be temporarily useful, 

 but could not be accepted as representing physical reality. 

 .Since that time, however, a variety of circumstances have 

 contributed to consolidate the Daltonian doctrine. The 

 o'Uimation of the ratios called atomic weights has been 

 the subject of research, attended by more and more 

 elaborate precautions to secure accuracy, from the time j 

 of Dalton himself onward through successive generations 

 down to the present day. Though the atomic weights of . 

 the majority of the common elements are now known to 

 a high degree of accuracy, the acknowledged errors have 

 been sufficiently great to render abortive various attempts 

 to reduce them to any common scheme of mathematical 

 relationship. .As is well known, the most important step 

 toward the systematisation of atomic weights was taken 

 about 1S60, mainly on the grounds eloquently and con- 

 vincingly set forth by Cannizzaro,' in consequence of 

 which the arbitrary selection of numbers for atomic weights 

 was superseded by the practical recognition of the law of 

 Avogadro and the application of the law of Dulong and 

 Petit, so that a common standard was established. No 

 general scheme of atomic weights was previously possible, 

 partial and imperfect efforts in this direction being repre- 

 sented by Dcebereiner's triads and the principle of homo- 

 logy made use of by Dumas. Only so soon as numbers 

 representing the atomic weights of calcium, barium, lead, 

 and other metals were corrected and brought into the 

 same category as those of oxygen, sulphur, and carbon 

 was there some chance of determining whether these 

 numbers possessed a common factor or were capable of 

 exhibiting mathematical inter-relations which might be re- 

 garded as symbolic of physical relations or even directly 

 1 iSfS, and Later, Faraday I eclure, 1872. 



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