May 5, 1904] 



NA TURE 



15 



ELEMENTS AND COMPOUNDS.' 

 T H.WE the honour of speaking to an audience of many 

 -'■ men whom I have long venerated as my intellectual, 

 although not my personal, teachers, and whom I admire as 

 h aders in our common work for science. But however 

 admirable the present, I am still more impressed by the 

 thought of the past associated with this place. When, not 

 long ago, I was engaged in electrochemical investigations 

 and almost daily sought for information and enlighten- 

 ment in Faraday's researches, I did not dare to think in 

 my boldest dreams that one day I should find myself stand- 

 ing on the very spot in which he was wont to give the 

 first accounts of the innumerable results of his indefatigable 

 labours, his indomitable zeal, and his inexorable love of 

 truth. 



.All that the pupil can do in such a case is to imbue 

 himself as completely as he can with the ideas of the master 

 and to try to perform his modest work in the master's 

 spirit. But here arises a new^ difficulty ; what subject ought 

 I to choose? When I look into my own humble efforts, I 

 find everywhere traces of Faraday. So far as relates to 

 electrochemistry, the thing is plain ; I think there is no 

 word that I have oftener spoken or written than the word 

 " ion," that word which was uttered for the first time in 

 its modern sense in this very spot. But in other fields in 

 which I have also worked, I feel the influence of his skilful 

 hands and his keen vision. Catalysis, which I have studied 

 during the past ten years, likewise came under his hands ; 

 and in the parts of the subject he worked at, the charm 

 of secrecy and ine.xplicableness has been exchanged for the 

 better qualities of a problem capable of resolution by earnest 

 workers. And in one subject which has engrossed a very 

 great part of my scientific activity, in the question of 

 energv, I find the venerated master again a leader. He 

 was indeed the first scientific man to direct all his investi- 

 gations in view of the idea of the conservation and the 

 mutual transformation of the various forces, as he called 

 them, or the various kinds of energy, as we call them now. 



This is a side of Faraday's mind to which, perhaps, not 

 so much attention has been paid as it des"rves. Although 

 doubtless the greatest advance — the discovery of the quanti- 

 tative proportionality between the energy which disappears 

 and that which originates — was due to Mayer and Joule 

 at a later date, yet the practical perception of this relation 

 was working in Faraday's mind long before. There is 

 indeed a great difference between the intellectual develop- 

 ment of a scientific truth to a degree sufficient for the dis- 

 coverer's ou'H work, and to the degree required for its 

 successful transfer to the minds of other workers. Faraday 

 contented himself in this case, as well as in others (for 

 example, in his conception of lines of force), with the first 

 step. But that he had reached this step and stood firmly 

 on it, that he used this conception constantly and regularly 

 in his work, is evident from his constant reference to it 

 from the first year of his scientific work onwards. From 

 a closer study of his lectures and papers we learn that in 

 every case he put the question : how can I change a given 

 force into another? This continued to the verv end of his 

 work ; for the last experiments he made related to the direct 

 conversion of gravity into electricity, and although he did 

 not succeed in his attempt, he was nevertheless convinced 

 of the possibility of the conversion. 



Guided by these considerations, I directed my attention 

 to the very earliest problems treated bv the master. Even 

 before F'araday held the chair of chemistry here in the 

 Royal Institution, as a youth of twenty-five years of age he 

 practised the art of a lecturer in a small club, the City 

 Philosophical Society, and the first course which he de- 

 livered there was on chemistry. In the sixteenth lecture, 

 after a description of the metals, he concluded with the 

 following general remarks : — • 



" To decompose the metals, then, to reform them, to 

 change them from one to another, and to realise the once 

 absurd notion of transmutation, are the problems now given 

 to the chemist for solution. Let none start at the difficult 

 task and think the means far bevond him ; everything may 

 be gained by energy and perseverance." And after a de- 

 scription of how in the course of history the means necessary 

 1 By Prof. W. Ostwald. Faraday Lecture delivered before the Fellows of 

 ihe Chemical Society in the Theatre of the Royal Institution on April ig. 



NO. I 80 1, VOL. 70] 



for the isolation of the metals from their combinations have 

 grown ever more and more efficacious, he mentioned the 

 recent great discoveries of his master Davy as follows : — 



" Lastly, glance but at the new, the extraordinary powers 

 which the chemist of our own nation put in action so 

 successfully for the reduction of the alkalies and the earths, 

 and you will no longer doubt that powers still more pro- 

 gressive and advanced may exist and put at some favour- 

 able moment the bases of the metals in our hands." 



When I try to follow this hint and take for the object 

 of our consideration the question of the nature of the 

 elements and of their compounds, I am aware that I am 

 not the first who has done so in this place. If I am not 

 mistaken, the very first chemist who had the honour of 

 addressing you as a Faraday lecturer, Jean-Baptiste Dumas, 

 lectured thirty-five years ago on the same subject. Never- 

 theless, I do not shrink from the repetition. Every gener- 

 ation of chemists must form its own views regarding this 

 fundamental problem of our science. The progress of science 

 shows itself in the way in which this is done. Faraday 

 was at this time fully influenced by Humphry Davy's 

 brilliant discoveries, and sought for the solution of the 

 problem in Davy's way. For Dumas, the most important 

 achievement of the science of his day was the systematising 

 of organic chemistry, condensed into the concept of homo- 

 logous series. He therefore regarded the elements as com- 

 parable with the hydrocarbon radicles, and tried to arrange 

 them in similar series with constant differences in the 

 numerical values of their atomic weights. It is well known 

 that these ideas finally developed into the great general- 

 isation we owe to Newlands, Lothar Meyer, and Mendel^eff. 

 Although the problem of the decomposition of the elements 

 was not solved in this way, these ideas proved to be most 

 efficient factors in the general development of science. 



From what store of ideas will a modern chemist derive 

 the new materials for a new answer to the old question? 

 A physicist will have a ready answer : he will construct 

 the elements in a mechanical way, or, if he is of the most 

 modern type, he will use electricity as timber. The chemist 

 will look on these structures with due respect indeed, but 

 with some reserve. Long experience has convinced chemists 

 (or at least some of them) that every hypothesis taken from 

 another science ultimately proves insufficient. They are 

 adapted to express certain sides of his, the chemist's, facts, 

 but on other not less important sides they fail, and the end 

 is inadequacy. Learning by this experience, he makes a 

 rule to use only chemical material for this work, and 

 according to this rule I propose to proceed. 



Hence, like Dumas, I put the question ; what are the 

 most important achievements of the chemistry of our day? 

 I do not hesitate to answer : chemical dynamics or the 

 theory of the progress of chemical reactions and the theory 

 of chemical equilibrium. What answer can chemical 

 dynamics give to the old question about the nature of the 

 chemical elements? 



The answer to this question sounds most remarkable ; and 

 to impress vou with the importance I ascribe to this in- 

 vestigation, I will mention the result at once : /( is possible, 

 to deduce from the principles of chemical dynamics all the 

 stoichiometrical laws; the law of constant proportions, the 

 law of multiple proportions and the law of combining 

 weights. You all know that up to the present time it has 

 only been possible to deduce these laws by help of the 

 atomic hypothesis. Chemical dynamics has, therefore, 

 made the atomic hypothesis unnecessary for this purpose, 

 and has put the theory of the stoichiometrical laws on more 

 secure ground than that furnished by a mere hypothesis. 



I am quite aware that in making this assertion I am 

 stepping on somewhat volcanic ground. I may be permitted 

 to guess that among this audience there are only very few 

 who would not at once answer, that they are quite satisfied 

 with the atoms as they are. and that they do not in the 

 least want to change them for any other conception. More- 

 over, I know that this very country is the birthplace of the 

 atomic hypothesis in its modern form, and that only a short 

 time ago the celebration of the centenary of the atomic 

 hypothesis has reminded you of the enormous advance wnich 

 science has made in this field during the last hundred years. 

 Therefore I have to make a great claim on your scientific 

 receptivity. But still I do not hesitate one moment to lay 

 the results of my work before you. For I feel quite sure 



