LIEBIG'S SCIENTIFIC ACHIEVEMENTS. 



G3 



had discovered that all gases unite chemically in 

 simple proportions, one to two, one to one, or two 

 to three, and so forth, and that the specific gravity 

 of compound chemical combinations in a state of 

 vapor supplies a check in analysis which became 

 of the greatest importance to organic chemistry. 

 Gay-Lussac had also invented the moist silver 

 test, so called, which is now used in all mints as 

 the only legal one. He had also materially im- 

 proved and completed the elementary analysis of 

 organic bodies begun by Lavoisier, and performed 

 many other services to science. 



Liebig would probably have preferred to be- 

 come the pupil of Gay-Lussac at once, but he did 

 not at that time take any young men into his 

 laboratory. Liebig, however, succeeded in gain- 

 ing entrance to Thenard's, at the Ecole Polytech- 

 nique, where he worked on at fulminating silver, 

 a preparation which played a part in his destiny, 

 for an unpleasant explosion in the house of his 

 principal, an apothecary at Heppenheim, speedily 

 diverted him from the pharmaceutical career on 

 which he entered on leaving the gymnasium. The 

 same preparation was the means of introducing 

 him to the sitting of the French Academy of Sci- 

 ences of 28th of July, 1823, which proved to be 

 of the greatest importance to him. He gave a 

 lecture on the analysis of Howard's fulminating 

 silver and quicksilver combinations. When the 

 sitting was over, while packing up his prepara- 

 tions, one of the members of the Academy 

 accosted him, and most kindly inquired about 

 his studies and plans. The stranger invited 

 him to dine with him in the Palais Royal, but, 

 either from shyness or inexperience, Liebig 

 omitted to ask who he was. There, however, he 

 made himself known ; it was Alexander von Hum- 

 boldt, who had just returned to Paris after a 

 long absence in Italy. He introduced his young 

 countryman, to whom he at once took a great 

 liking, to his friend Gay-Lussac, for he knew 

 from experience the benefit of working with him. 

 In 1804 he had published memoirs in conjunction 

 with him on the analysis of the air, and had after- 

 ward worked with him on the proportions in 

 which gases combine chemically. 



The time spent with Gay-Lussac was the 

 bright spot during Liebig's student-years. How 

 these two gifted men must have enjoyed each 

 other's society may be imagined. The one was 

 about forty-five, in the very prime of his powers, 

 and had attained the highest position, a tree 

 laden with precious fruit ; the other was scarcely 

 twenty, in the bloom of youth, a sapling full of 

 promise, whose future might be even then antici- 



pated, and was anticipated, by himself. Liebig 

 once related of Gay-Lussac that when they had 

 made an interesting discovery, or completed a 

 difficult analysis successfully, he had often taken 

 hold of him and danced round the table with him 

 in the laboratory. 



The kind of reports that Gay-Lussac must 

 have given to his friend Humboldt of the young 

 Darmstadt chemist may be imagined, and we 

 shall not therefore be surprised that on Liebig's 

 leaving Paris, in 1824, Humboldt recommended 

 him so highly to the Grand-duke Louis I. that, 

 in the same year, without taking the vote of the 

 university, he appointed him Professor Extraor- 

 dinary of Chemistry at Giessen. Neither need 

 we be surprised that he was regarded by his older 

 colleagues as an upstart and protege, and that he 

 did not find much support in reforming the chemi- 

 cal school and faculty. 



But Liebig overcame all difficulties. Two 

 years later he was made Ordinary Professor of 

 Chemistry. He made the best arrangements that 

 he could for himself and his pupils, to a great 

 extent at his own expense. His reputation in- 

 creased rapidly, but it was not till it became so 

 great that young chemists came to him from all 

 parts of Europe that the Government resolved to 

 build a larger chemical laboratory on the Selter- 

 ser Berg, outside the gates of Giessen. 



To describe Liebig's scientific labors from 

 1824 to 1851 at Giessen, and from 1852 to 18T3 

 at Munich, would be a task beyond our limits. 

 All that can be done is to seize on some salient 

 features to give an idea of his method of working. 



His labors may be divided into two parts, 

 both as to time and subject : the first, from 1824 

 to 1839, when they were mainly devoted to pure 

 chemistry ; the second, from 1840, when his at- 

 tention began to be directed to the application of 

 chemistry to agriculture and physiology ; there 

 was, however, much preparation for this in the 

 first period, and researches in pure chemistry oc- 

 cur also in the second. 



There was scarcely a branch of chemistry to 

 which Liebig did not devote attention, and which 

 was not enriched by him. Except Berzelius, I 

 know of no chemist who pursued so many inves- 

 tigations. The Annals of Chemistry and Phar- 

 macy, edited by him and others, contain more 

 than two hundred treatises by Liebig on the 

 most various branches of pure and practical 

 chemistry. Far be it from me to estimate a sci- 

 entific man by the number of his writings, but, 

 considering the quality of Liebig's, their number 

 is the more remarkable. 



