366 



NA TURE 



[August 9, 1906 



the present demand for the material. It has also to be 

 remembered that the actual cost of producing raw rubber, 

 which is at present about one shilling per pound, will 

 probably be reduced, and the market price of rubber may 

 eventually be so considerably lowered that, as with quinine, 

 the synthetic production could not be profitably carried 

 on. That is a question which involves many factors at 

 present unknown, and only time can decide. Chemists 

 may, however, confidently predict that before the British 

 Association again meets at York the synthetic production 

 of rubber will be a fully accomplished fact. 



ks I have said, our science is concerned with nearly 

 every problem connected with the great rubber industry, 

 and in concluding these few remarks I may allude to the 

 production of vulcanised rubber depending on the form- 

 ation of additive compounds of the hydrocarbon with 

 sulphur. In this connection I should mention the recent 

 experiments of Mr. Bamber in Ceylon, which appear to 

 show that vulcanisation may be accomplished by acting on 

 the uncoagulated latex with chloride of sulphur. If this 

 proves to be practicable, it may mean the transference to 

 the tropics of the subsidiary industry of vulcanisation, 

 which is at present carried on in Europe. 



Owing to the importance and interest which attach to 

 the chemistry of rubber, it is to form an important feature 

 in the work of this Section at the York Meeting. Papers 

 will be contributed by some of the best known workers in 

 ■this field, by Prof, filden, and by Prof. Harries, of Kiel, 

 who will give an account of his recent work ; whilst Mr. 

 Pickles, of the Imperial Institute, will present a report 

 summarising the whole of our chemical knowledge of the 

 subject. 



The chemical investigation of raw materials often raises, 

 unexpectedly, problems of great scientific interest. The 

 examination at the Imperial Institute of the seeds of the 

 Para rubber tree (Hevea brasiUensis) has shown that they 

 contain what proves to be a valuable drving oil, and in the 

 course of the investigation it was ascertained that there 

 is also present in the seeds an enzvme closely allied to, 

 if not identical with, lipase, which is capable 'of splitting 

 the oil by hydrolysis into glycerin and the free fatty acid. 

 Subsequently, during the examination of other oil seeds 

 similar enzymes have been detected, and it would appear 

 probable that most oil seeds may prove to contain an 

 enzyme capable of decomposing the fatty constituent. 



Another subject of great chemical interest and botanical 

 irnportance which has come into prominence in connection 

 with the Indian and Colonial work of the Imperial Insti- 

 tute is to be included in a joint discussion which has been 

 arranged with the Section of Botany. I refer to the pro- 

 duction of prussic acid by plants, which, as I have else- 

 where suggested, it is convenient to refer to as cyano- 

 genesis. In this discussion we shall have the advantage 

 of the cooperation of Prof. Van Romburgh and Dr. 

 Greshoff, whose work with Dr. Treub of Java on this 

 subject is known to chemists and botanists alike. The 

 history of the origin of the several investigations in which 

 Dr. Henry has been associated with me is not without 

 mterest in connection with the principal subject of this 

 Address. During the first British expedition to the Sudan 

 agamst the Mahdi a number of transport animals were 

 poisoned through eating a small vetch which springs up 

 in the Nile Valley during the fall of the river. The plant 

 (Lotus arabiciis) is well known to the .Arabs, by whom it 

 is cut when fully grown, and used as fodder for animals. 



The results of the investigation of this matter which 

 were communicated to the Royal Societv proved that the 

 young plant generated prussic acid when crushed with 

 water. It was found to contain a new glucoside, lotusin, 

 together with an enzyme capable of decomposing it into 

 prussic acid, dextrose, and a yellow colouring matter, 

 lotofiavin. 



The glucoside is of special chemical interest, as being 

 the only one known which contains the cvanogen group 

 attached in the molecule to the sugar residue. Further 

 investigation has shown that other "fodder plants which 

 are occasionally poisonous owe this character to the exist- 

 ence of other cyanogenetic glucosides. In a series of papers 

 communicated to the Royal Society, Dr. Henry and I 

 have described the properties and constitution of dhurrin 

 NO. 191 9, VOL. 74] 



from Sorghum vulgare, and of phaseolunatin, which we 

 have shown to be responsible for the production of prussic 

 acid by Phaseolus luiiatus (Lima beans), Manihot 

 utilissima (cassava or tapioca), and by linseed (the flax 

 plant). Phaseolunatin is remarkable in furnishing acetone 

 as one of its products of hydrolysis. The investigation, 

 besides fulfilling the primary purpose for which it was 

 carried out, has raised a host of problems ; — as to the 

 constitution of glucosides, the nature of the enzymes which 

 accompany them in the plants, and also in relation to the 

 fundamental question of plant metabolism. 



.•Another subject of Imperial as well as National import- 

 ance is to be the subject of a joint discussion with the 

 Section of Physiology. I refer to the problem of diet. 

 As chemists we are interested in this subject chiefly from 

 the point of view of the composition of foods, and of the 

 molecular structure which is associated with dietetic value. 

 The first attempt to deal with the matter from the scientific 

 side was made by a great chemist, Liebig. We are now 

 in a position to investigate the problem more minutely, 

 and the work of American physiologists has already led to 

 important results. We have still to learn how materials 

 such as rice and potatoes, which are nearly free from 

 proteids, continue nevertheless to serve as the main diet 

 of large numbers of people. It would seem that the best 

 plan of operations will be for physiologists to settle by 

 the accurate methods now available the precise value of 

 typical foodstuffs, and for the chemist to deal with these 

 in relation to their composition, and finally with reference 

 to the constitution of their constituents. The time has come 

 when an advance must be made from the chemical side in 

 the analytical methods employed for gauging the value of 

 food materials. 



I feel that I have said much, but that I have left still 

 more unsaid on many topics. I must leave almost un- 

 touched the entire subject of mineral chemistry, which is 

 not only important in connection with the determination 

 of the resources of India and the Colonies, but is also a 

 subject somewhat neglected on its chemical side, which 

 has been recently brought into prominence through the 

 discovery of radio-activity. 



The new radio-active mineral thorianite, from Ceylon, 

 of which Mr. Blake and I have given an account to the 

 Royal Society-, brings me at once to a subject which raises 

 the most fundamental of chemical questions, the nature of 

 the elements and of the atom. The recent discussions 

 of this subject have become so purely speculative that, 

 whilst chemistry is bound to follow the lead of physics in 

 this matter, chemists are inclined to consider that more 

 well-ascertained facts are needed for any further discussion 

 to be profitable from the chemical side. 



In this Address I have ventured to urge the fuller 

 recognition by Government of the scientific method as a 

 powerful instrument in promoting the commercial develop- 

 ment of the Colonies, and I have drawn attention to the 

 important part the science of chemistry can play in the 

 Imperial work of developing the resources of our 

 Possessions. 



No apology is needed in this place for directing attention 

 to a subject which involves a most important practical 

 application of our science, since one of the principal func- 

 tions of the British Association is to bring science into 

 close touch with the problems of our national life, and to 

 interest the general public in the application of science to 

 their solution. 



I have, however, also shown that many problems of the 

 highest scientific interest arise in connection with the 

 investigation of these economic problems. 



NOTES. 

 A DEPARTMENTAL committee has been appointed by the 

 Home Secretary to inquire and report what diseases and 

 injuries, other than injuries by accident, are due to in- 

 dustrial occupations, are distinguishable as such, and can 

 properly be added to the diseases enumerated in the third 

 schedule of the Workmen's Compensation Bill, 1906, so 

 as to entitle to compensation persons who may be affected 



