A GLASS OF WATER. 56 3 



The most difficult task for chemistry was the investigation of the 

 laws of life. All that was known in regard to this was, that the living 

 organisms of the animal and vegetable kingdoms consisted of a few 

 elements, say three or four, which were the same in both. The differ- 

 ence, then, in the manifold organisms of the kingdoms must needs be 

 quantitative; and here the first want was an accurate method of 

 analysis. This presented a difficult problem. The first successful ex- 

 periments date back as far as 1809, but the method of determining 

 weight was as yet so complicated and wasteful of time, and required 

 so much skill and practice, that only a few substances could be ana- 

 lyzed. To investigate the two organic kingdoms with greater hope 

 of success, an easier method of analysis must be found, and here we 

 meet the name of a man whom Germany proudly calls her own. 



To Justus Liebig belongs the merit of having discovered a method 

 by which, without loss of accuracy, the whole process was greatly 

 simplified, and of which he himself made extensive use. As his great 

 teacher, Gay-Lussac, had done before him, he burned the organic sub- 

 stance to be analyzed, in a dry glass tube with oxide of copper, con- 

 densed the resultant water in an apparatus containing a water- absorb- 

 ing salt, calcium chloride, and the resultant carbonic acid was ab- 

 sorbed in a glass of water. This last was a glass of a peculiar shape, 

 with a clear liquid consisting of an aqueous solution of pure caustic 

 potash. This glass of water, which has rendered such great services to 

 humanity, bears the name of " Liebig's potash apparatus," and appears 

 on his pictures as interwoven with the clouds of the higher regions, 

 thus enabling the chemist to recognize the portrait even without the 

 signature. 



By that simplified method and by the aid of the labors of his many 

 talented students, who now adorn most of the chairs of chemistry in 

 Europe, as well as through the geniality of the master, the immense 

 material from which he reared the structure of organic chemistry 

 could be collected and properly used. Agricultural chemistry may be 

 considered a part of organic chemistry ; its province is to determine 

 the laws of the growth of plants. The year 1840 is of the same im- 

 portance in the history of the world as the years 1436, 1492, and 1774, 

 which mark the invention of printing, the discovery of America, and 

 that of oxygen. 



A report upon the application of chemistry to agriculture, which 

 Liebig had agreed to prepare for the British Association for the Ad- 

 vancement of Science, convinced him of the fact that the then exist- 

 ing views regarding this subject consisted mainly of errors. Instead, 

 therefore, of reporting upon agricultural chemistry, he must first create 

 the science. He demonstrated this in the ever-memorable repoi't which 

 may be said to contain nearly three-fourths of the agricultural chemis- 

 try of the present day. The immense materials collected by him and 

 his assistants were of excellent service in this work, for they had 



