THE INFLUENCE OF CHEMISTRY. 91 



of all kinds of substances ; it controlled the' proper selection 

 of suitable subjects for future inquiry, and caused a more 

 judicious choice of means to obtain the needed information. 



Among the first important results of the application of 

 careful quantitative modes of examination are found the de- 

 termination of the composition of water, the analysis of the 

 air, and a correct experimental demonstration of the function 

 of the air in the process of ordinary combustion, as well as 

 of animal respiration, information of the first impoitance 

 regarding the topic under discussion. 



For nearly thirty years, until 1820, inorganic su1> 

 stances almost exclusively engaged the attention of chemists. 



The gradual perfection of analytical modes for the exami- 

 nation of inorganic substances had led to the discovery of 

 many new elements. The study of their chemical and phys- 

 ical properties, as well as of their relations to previously 

 known elementary substances ; the analyses of minerals, of 

 soils, of the ashes of plants, and of industrial products in gen- 

 eral, had furnished abundant subjects for investigation during 

 that period. Organic substances, on account of inefiicient 

 modes of analysis, had received but little attention ; com- 

 paratively but a few chemists had devoted themselves thus 

 far to the study of organic compounds. Most noteworthy 

 among them were Thenard and Gay-Lussac, two distin- 

 guished French chemists, who followed the course pointed 

 out by Lavoisier. The unsatisfactory condition of organic 

 chemistry was to be changed materially by the genius and 

 the indomitable will of one man, who at this stage of the his- 

 tory of chemistry entered the field of chemical research — 

 Justus von Liebig. As the scientific labors of this remarka- 

 ble man arc closely identified with the development of the 

 science of animal nutrition, I may be pardoned for treating 

 somewhat more in detail of the circumstances which led him 

 to exert a controlling infiuence on our present views regard- 

 ing the science of stock-feeding. Having pursued the study 

 of chemistry for four years at Gorman universities, he had 

 the good fortune to work for two years in the laboratory of 

 Gay-Lussac at Paris, the most skilful experimenter in 

 organic chemistry of the time. 



Naturally inclined to the study of organic su'-stances, he 



