LIE BIO'S SCIENTIFIC ACHIEVEMENTS. 



65 



arsenic sulphide, etc., and can be eliminated 

 from it. 



Berzelius, who, even when treating of chemi- 

 cal achievements in his annual reports, was wont 

 to express himself in measured and stately 

 phrase, was betrayed into unusual warmth by 

 this discovery, and says in a letter (vol. xxvi. of 

 Poggendorff's Annals): 



" The facts demonstrated give rise to so many 

 considerations that they may be called the dawn 

 of a new day in vegetable chemistry. I therefore 

 suggest that the first compound radical, consisting 

 of more than two simple bodies in chemical com- 

 bination, be called Proin, from irpan, dawn, day- 

 break, or Orthrin, from opflpdy, early twilight." 



Berzelius had almost turned poet. 



If the theory of organic radicals seems to be, 

 to a great extent, superseded by her blooming 

 daughters, the older type, and the modern struct- 

 ural chemistry, this does not invalidate Liebig's 

 services to organic chemistry, for the period when 

 the radical theory prevailed was one of great 

 progress ; it was in fact a mother, whose features 

 are to a great extent reproduced in those of her 

 daughters. Every theory which leads to discovery 

 and research has its value ; thus the Phlogiston 

 theory of Stahl in the last century gave an impe- 

 tus to progress, although, before its close, it was 

 forever exploded by Lavoisier. Even the present 

 doctrine of the chemical structure of combinations 

 and the arrangement of atoms is certainly not 

 the last word in organic chemistry, and I doubt 

 if it will prevail much longer than its predecessor 

 the Type theory. I am not sufficiently versed in 

 modern chemistry to form an opinion, but I 

 should not be surprised if at last the various 

 theories, which are all daughters of the radical 

 theory, should, so to speak, return to their 

 mother's bosom, somewhat altered, perhaps, and 

 rich in experience and achievements. 



When we consider the numerous researches 

 in organic chemistry which Liebig made alone or 

 with others, we cannot be surprised that he was 

 looked upon as preeminent in this department, 

 and can only wonder that he found strength and 

 time for the gigantic labors it involved. 



The strength was the gift of Nature, but the 

 time was the result of his diligence and method. 

 Liebig's understanding was as acute as his imagi- 

 nation was fertile, yet he was by no means vision- 

 ary. Intellect and imagination were harmoniously 

 blended in his character, and had, perhaps, the 

 chief share in his success both in science and 

 life. You should have seen Liebig examine a 

 substance or watch a chemical process ; he was 



sharp-sighted in every sense of the word. I was 

 once present when a crystalline, colorless body 

 was brought to him, which had just been found in 

 pyroligneous acid, and the composition of which 

 had not been ascertained. It smelt like creosote, 

 and, as the presence of that body in pyroligneous 

 acid had not hitherto been detected, Liebig was 

 interested in it. He laid it on a platina plate and 

 held it over a flame ; it melted, steamed a little, 

 and when removed from the fire resumed a crys- 

 talline form. Liebig said at once, "I think it 

 is pyrogallic acid, for that melts and crystallizes 

 as this does." It was a bold conjecture, and one 

 that an orthodox chemist would not have vent- 

 ured on. For it was not known that pyrogallic 

 acid occurred in pyroligneous acid, and it is with- 

 out smell, or at any rate has not the least smell 

 of creosote, while so many bodies melt and crys- 

 tallize afterward that more than ordinary acute- 

 ness is required to detect peculiarities which fur- 

 nish hints for diagnosis. The substance was dis- 

 solved in water and tested with the reagents for 

 pyrogallic acid. All the reactions occurred ; 

 there was no doubt that it was pyrogallic acid or 

 something closely allied to it. All this occupied 

 less than ten minutes, and further investigation 

 confirmed Liebig's opinion, for, though not pyro- 

 gallic acid, it was catcchuic acid, which is closely 

 allied to it. 



It was only natural that one who so often 

 found that he saw farther than others should not 

 readily give up anything that he had taken into 

 his head, even if experiment did not at once con- 

 firm his views ; no man is infallible, and Liebig 

 was now and then mistaken. When he thought 

 that a substance contained this or that, he often 

 gave it to one of his trusted pupils to experiment 

 upon. If he did not at once find what was ex- 

 pected, Liebig was apt to doubt his pupil's skill 

 rather than his own conjectures. He would 

 naively say, " But you must find it." If unable 

 to do so, he sank still lower in his master's esti- 

 mation, but rose again as quickly if he produced 

 indisputable evMence against his opinion, or some 

 other explanation. As was natural, the tenacity 

 with which he held to his own opinion increased 

 with years. Learned men in other departments, 

 particularly men of book-knowledge, had much 

 ado to stand their ground against the ideas on 

 their special subjects which Liebig would throw 

 out in conversation. Though they might argue 

 the point with faultless language and logic, he 

 was seldom convinced. He would say, " The 

 man is much more learned than I am," or, " He 

 knows a great deal more than I do ; " but he still 



