220 



NATURE 



[November 6, igig 



prepared several pounds of it, in Leipzig", in the 

 autumn of 1868, I was regarded with wonder: 

 Squire and Messel began its manufacture here at 

 Silvertown in 1873 : it soon came into vogue, 

 especially in the alizarin industry. During the 

 war, many thousands of tons have been used in 

 the production of propellants and high explosives. 

 I then also made the chlorhydrol, SO3HCI, in 

 quantity, and suggested to my student friend, 

 Karl Knapp, Liebig's nephew, that he should test 

 its value as a sulphonating agent. He sulphon- 

 ated benzene. I took up the work afterwards and 

 first applied it to toluene, so laying the foundation 

 of the method now preferred in manufacturing 

 saccharin. 



In 1868 chemists were waxing enthusiastic over 

 Mendeleeff's great generalisation, brought home to 

 us not only in his paper in the Annalen but also 

 by Lothar Meyer's well-known book, then recently 

 published, especially by Meyer's justly famed 

 atomic volume curve. At that date those of us 

 who could think in terms of systematic organic 

 chemistry were possessed by the view that the 

 "elements " must be compounds : the "periodic " 

 inter-relationships were so similar to those mani- 

 fest in homologous and isologous series. Soddy's 

 " isotopes " — the word is unnecessary — are 

 simply the chemist's homologues. That the two 

 leads should be as like as the two Dromios — 

 recent observation shows that they are perceptibly 

 different — is in no way surprising : methane and 

 ethane are all but indistinguishable chemically ; 

 we can also foresee isomeric as well as homo- 

 logous primaries. Now that the "primaries" 

 have been robbed of their position as "atomic" 

 materials, by the appearance on the scene of 

 radium, this view is proved to have been justified ; 

 but none of us ever dreamt that they would come 

 to be regarded as made of lumps of electricity — 

 still less tfTat we should ever dare to think of 

 energy in terms of quanta or to discard the 

 doctrine of the other in favour of one of relativity. 



All my life, I have regretted the aloofness of 

 chemistry from physics : that the physicist shows 

 so little real interest in chemistry. It is a welcome 

 finish to find him at last entering upon the fringe 

 of our domain and taking up our work, though it 

 is a pity he cannot become one of us instead of a 

 mere extrapolation ; probably it cannot well be 

 otherwise, as the mathematical habit of mind is 

 required for the new work and chemist and 

 mathematician are different natures. Ours must 

 be the task of digesting the material to the point 

 at which our mental enzymic machinery no longer 

 suffices and that of the mathematician and 

 physicist comes into play. The two recent lec- 

 tures to the Chemical Society by Nicholson and 

 Jeans — both astounding displays of eloquence and 

 imaginative power — are demonstrative of the new 

 departure. If fifty years hence the new field be 

 as fully grasped as that has now been which I 

 saw opening up in 1868, Nature at its centenary 

 will indeed have cause to congratulate its readers. 



In 1868, we were only beginning to write 

 C=i2; our symbolic system was barely stabi- 

 NO. 2610, VOL. 104] 



Used; the importance of Avogadro's theorem 

 was but coming home to us, mainly through 

 Cannizzaro's insistence. Structural constitutional 

 chemistry was in its infancy. Frankland's theory 

 of valency — it is now clear that he included carbon 

 in his scheme — and Kekule's benzene symbol were 

 new weapons ; we were only beginning to inter- 

 pret isomerism in terms of structure ; we scarcely 

 thought of position as its cause. A vast edifice 

 has been erected in the interval but the founda- 

 tions are simple: Frankland's postulates have 

 but been supplemented by van't Hoff's extension 

 of Pasteur's geometric conceptions. What is most 

 noteworthy is the surprising simplicity and suffi- 

 ciency of the system. 



Latterly we have begun to think in terms of 

 solid structure : it is already clear that the next 

 advance will come from the geometric, crystallo- 

 graphic side : and having learnt to see through 

 a brick wall, we are now beginning to peer 

 directly into the molecular structure of crystalline 

 soliys. Low temperature phenomena have been 

 probed to their depths, especially in this country ; 

 indeed, we have seen a series of important indus- 

 tries grow out of the work. 



The growth of our knowledge of method, of 

 our analytic and synthetic powers, has been mar- 

 vellous — full use has been made of this develop- 

 ment by the manufacturer, so that we can now 

 not only reproduce natural colouring matters but 

 match the rainbow in every tint. Although British 

 chemists cannot claim the credit of much of the 

 matching, they can at least rejoice in the fact 

 that the foundations were laid in London^ — by 

 Faraday's discovery of benzene in 1825, in Albe- 

 marle Street; and by Perkin's discovery of mauve, 

 in Oxford Street and at Sudbury in 1856. 



It is noteworthy that mauve was made in at- 

 tempting to synthesise quinine : as we are not 

 yet certain as to the structure of this alkaloid 

 and in no way near to a method of producing it 

 artificially, it is clear that even now our powers 

 of interrogating and copying Nature are but 

 limited : remarkable as our progress has been, 

 she yet defies us in many directions. We stand 

 ashamed before the unassuming ease with which 

 she fabricates starch from glucose underground in 

 the dark; indeed, cane-sugar, starch, cellulose 

 and not a few other compounds of primary im- 

 portance are still to be ranged with the Delphic 

 mysteries. 



But whilst, on the organic side, we have 

 secured a wonderful mastery and the odds in 

 favour of our structural conceptions are many 

 thousands to one — because we have been able to 

 ring the changes so often with success ; on the 

 inorganic side, almost complete ignorance pre- 

 vails — because we have not been able to ring the 

 changes. Thus we cannot say, with any approach 

 to certainty, what is the structure of so simple a 

 substance as sulphuric acid. In this and similar 

 cases probably the clue will come through X-rays. 



On the biological side the advance has been very 

 great and it can no longer be said with truth 

 that "Thierchemie ist Schmierchemie " — Emil 



