620 HISTORY OF SCIENCE. 



tories of the present day, and many of our most eminent chemists 

 were his pupils and assistants. He made many important discoveries, 

 adding in fact a new domain to the province of chemistry. He invented 

 new processes and new apparatus ; he expounded lucid theories of 

 combination ; his investigations made possible new manufactures ; he 

 extended the resources of the agriculturist ; he carried chemistry into 

 the field of physiology. 



Liebig kept several terms as a student at the University of Bonn, 

 but obtained his degree of Ph.D. at Erlangen when he was nineteen 

 years of age. Being desirous of pursuing the experimental study of 

 chemistry at Paris, which was then the great centre of chemical science, 

 he was provided by the reigning Grand Duke of Hesse-Darmstadt 

 with the means for several years' residence in the French capital. A 

 number of chemists of high genius were then cultivating this science 

 with brilliant success on the banks of the Seine. There among others 

 were Gay-Lussac, Thenard, Chevreul, and Dulong. By the influence 

 of his countryman, Alexander von Humboldt, young Liebig obtained 

 admittance into the laboratories of Gay-Lussac, Dulong, and Thenard. 

 In 1823 Liebig published his first paper, relating to certain fulmina- 

 ting compounds, and in the following year a paper appeared on the 

 same subject under the joint name of Liebig and Gay-Lussac. In the 

 same year Liebig was, on Humboldt's recommendation, appointed 

 Professor of Chemistry in the little University of Giessen, where, from 

 a very insignificant foundation, he raised the most famous school of 

 practical chemistry in Germany. 



The researches on fulminates which Liebig instituted in conjunction 

 with Gay-Lussac proved that these compounds had the same per-cen- 

 tage composition as another class of substances called cyanates, without, 

 however, being identical with them. An example of the way in which 

 this is theoretically possible will be seen in a list of some polymeric 

 hydro-carbons on a subsequent page. This led Liebig to the study of 

 the cyanates and the allied compounds, the cyanides. The starting- 

 point of the group is a well-known substance of extensive use in the 

 arts, called the yellow prussia.te of potash. Liebig's researches explained 

 and improved the mode of preparing this substance, and he further 

 devised a simple and cheap process for obtaining cyanide of potassium 

 from the yellow prussiate. This method is now followed out on the large 

 scale, for cyanide of potassium is very extensively used in photography 

 and in electro-plating. These cyanogen compounds formed the starting- 

 point of a long series of theoretically interesting new compounds, with 

 which Liebig endowed organic chemistry. Another very interesting 

 group of substances studied by Liebig in conjunction with Wohler was 

 the benzoic compounds, which form the pivots, as it were, upon which 

 turn a vast series of compounds. Liebig investigated the nature of many 

 organic acids with signal success. The derivatives of alcohol formed an- 

 other subject of inquiry; but as the statement of results and methods 



