1892.] NEW YORK ACADEMY OF SCIENCES. 115 



research, for he had already made oxindole from phenylacetic acid, 

 which in turn is made from some of the coal-tar products. The 

 synthesis is complete, although tedious. 



" The artificial formation of oil of mustard is another triumph 

 of synthetic organic chemistry. In distilling glycerin and oxalic 

 acid" the chief product obtained is formic acid ; but the rest of the 

 products of decomposition were unknown until Tollens, the chemist, 

 undertook to investigate them. He found that, besides formic acid, 

 there was also produced a considerable quantity of allyl alcohol. 

 Now this alcohol is one of the principal constituents of oil of mus- 

 tard, but nobody knew of an economical method of preparing it 

 until Tollens showed that it could be produced from glycerin and 

 oxalic acid. It can now be made in any quantity and readily con- 

 verted into oil of mu.stard. 



Citric acid, usually made from lemons and limes, can also be 

 made artificially. 



Glycerin is the starting-point. 



Glycerin is treated with chlorine, and gives what is called a 

 dichlorhydriu. This dichlorhydrin is oxidized with chromic acid, 

 and gives an acetone ; this acetoue is treated with hydrocyanic acid, 

 then with hydrochloric acid, then with sodium, then with potas- 

 sium cyanide, and finally with hydrochloric acid, which gives citric 

 acid. 



Of course, the process is too complicated to be useful ; but the 

 synthesis or building up of the organic acid from glycerin is an 

 accomplished fact. 



Taurine, the acid of bile ; salicin ; piperidine, the active principle 

 of black pepper; uric acid; tyrosine, a product of the spleen, liver, 

 urine, etc. ; vanilline, the aromatic principle of the vanilla bean ; 

 cumarine, of the tonka bean ; daphnetine and umbelliferone, natural 

 glucosides; and other bodies that it is unnecessary to mention, are 

 all the products of modern 'organic synthesis. 



Furthermore, in the search after the constitution of organic com- 

 pounds we are often led to discover bodies, hitherto unknown to 

 man, with many new and valuable properties. 



At the beginning of the lecture I spoke of the use of distillation 

 by the old chemists and apothecaries as a means of obtaining the 

 active principles of substances. During the seventeenth century a 

 man named Dippel applied this process to certain fetid animal oils, 

 obtained from stag's horns, and the product was long known in the 

 apothecary's store as Dippel's oil or bone-oil. 



About the year 1846, Anderson, a Scotch chemist, discovered in 

 this Dippel's oil certain basic oily bodies that resenil)led ammonia 

 in their property of containing nitrogen. Little attention was paid 

 to this fact. 



In the year 1834, Runge, a German chemist, discovered a series 

 of bases in the distillates from coal-tar ; and about the same time, 

 or a little later, Greville Williams, an English chemist, located these 



