804 



SCIENCE. 



[N. S. Vol. XX. No. 519. 



stance of the saponification process by means 

 of lime. In order to hydrolyze (saponify) 

 a fat by means of lime in an open vat the 

 theoretical quantity of CaO, namely, 9.7 per 

 cent., was not sufficient to produce complete 

 saponification, and no less than 12 to 14 per 

 cent, were necessary to completely convert tri- 

 glyceride into glycerol and the calcium salts 

 of fatty acids. If the view were correct that 

 the lime acts as an accelerator, then it should 

 be possible to completely hydrolyze a tri- 

 glyceride by a smaller amount of the base 

 than theory requires for the complete satura- 

 tion of the fatty acids. The theory further 

 predicts that if the temperature and the pres- 

 sure under which the reaction is carried out 

 are increased, the amount of base may be re- 

 duced. As this is borne out by the methods 

 practised on a large scale in which practically 

 complete saponification is effected with from 

 one to three per cent, of lime under pressures 

 of twelve to eight atmospheres, the view that 

 the bases act as accelerators was amply eon- 

 firmed. 



On the strength of the foregoing views one 

 could give a rational explanation of the phe- 

 nomenon of rancidity. In the first instance 

 the triglycerides were hydrolyzed by the 

 minute quantities of moisture which always 

 found access to thin fats, however carefully 

 they might be preserved. He likened the 

 slow hydrolysis to the slow decomposition of 

 granite in the course of centuries. The free 

 fatty acids thus formed were then degraded 

 in a secondary reaction into lower volatile 

 acids, on being oxidized by the oxygen of the 

 air, thereby acquiring that disagreeable taste 

 and smell which we comprise under the term 

 ' rancidity.' 



Dr. Lewkowits.ch next touched upon the 

 discovery of mixed triglycerides in natural 

 oils and fats. He first showed that theory 

 predicted the existence of two isomeric mono- 

 glycerides, as also of two isomeric diglycerides 

 having the same acid radical. Triglycerides, 

 in which all three acid radicals had the same 

 composition, could exist in only one form. 



Thus in case two different acid radicals are 

 combined with one molecule of glycerol, then 

 theory predicted the existence of two isomer- 



ides, and if all three fatty acid radicals in 

 one molecule of a triglyceride were different, 

 then three diffei'ent substances could exist. 



The last-named class of glycerides was ap- 

 propriately termed ' mixed glycerides.' The 

 occurrence of such glycerides has been proved 

 hitherto in a number of cases. Thus they 

 were shown to exist in Kokum butter, cacao 

 butter, olive oil, tallows, lard and human fat. 

 The enormous amount of theoretically pos- 

 sible triglycerides opened out a wide vista of 

 researches that would undoubtedly lead to 

 important results in the near future. 



Discussion. — In reply to Professor Bogert, 

 Dr. Lewkowitsch said that it was almost cer- 

 tain that lecithin contained several fatty acid 

 radicals in one molecule. 



In reply to Dr. Ittner, Dr. Lewkowitsch 

 agreed that optically active glycerides should 

 exist theoretically, and he pointed to some 

 work he had carried out over twenty years 

 ago, when, basing himself on such theoretical 

 considerations, he had resolved glyceric acid 

 into two optically active components. As re- 

 gards the acidic component of the glycerides, 

 the fatty acids themselves had hitherto, with 

 the exception of ricinoleic acid, been found 

 optically inactive, but a few months ago Dr. 

 Power had discovered in Chaulmoogra oil a 

 new class of fatty acids, which were remark- 

 able not only for containing a closed carbon 

 ring, but also for exhibiting the property of 

 rotating the plane of polarized light. 



In reply to the chairman. Dr. Lewkowitsch 

 pointed out that hydrolysis in alcoholic solu- 

 tion need not be looked upon as differing from 

 the hydrolysis occurring in aqueous solution, 

 if one looked upon C^H, as being a basic ion. 

 He himself thought that under pressure the 

 conversion of a glyceride into ethylic esters 

 might be carried out to a large extent, al- 

 though, judging from the classical researches 

 of Berthelot and Pean St. Giles he would not 

 expect the reaction to be a complete one. The 

 reaction may be explained by the two groups 

 CJIj and R changing places. The correctness 

 of this view was proved by the fact, that if a 

 fat was saponified in alcoholic solution in an 

 insufficient amount of KOH, ethylic esters 

 were obtained as the immediate products of 



