378 MEMOIR OF LOUIS JACQUES THENAED. 



were able to announce to tlie Academy that by means of the ordinary affinities 

 tliey had succeeded in obtaining new substances more abundantly than by tbe 

 pile. By employing- potassium and sodium, they effected tlie isolation of a new 

 and simple substance, which they named boron. 



Davy recognized the superiority of the chemical method for the extraction 

 of metals ; but he claimed this boron as an element which had come to light 

 through his own investigations. This Thcnard and Gay Lussac would by no 

 means concede, and they were right ; but they maintained at the same time 

 that sodium and potassium, so far from being simple bodies, were combinations 

 of alkalies with hydrogen, or hydrurets. Their English rival justly answered 

 that, if they adhered to this theory, it would follow of course that their simple 

 principle of boron was but a hijdrurci of horic acid — an argument which re- 

 mained unanswered. This, however, was the commencement of a discussion 

 which, with profit to science and ciedit to both countries, continued for not less 

 than five years, and Avhich marks the epoch at which the basis of existing ideas 

 respecting simple bodies Avas definitely fixed. 



In one of the memoirs in which Uiey rendered an account of the different 

 aspects of their controversy with the English savant, Thenard and Gay Lussac 

 had said : "The conjecture is not inadmissible that oxygenated muriatic acid 

 is a simple body." It was not without having first tested this acid with potas- 

 sium, and strenuously sought to extort some evidence of oxygen, that they gave 

 expression to such an opinion. For, if oxygenated muriatic acid were ad- 

 mitted to be a simple body, a new principle of acidification would be disclosed, 

 and a serious breach be thus made in the theory of Lavoisier. Recoiling 

 from tins consequence, and restrained moreover by the immovable opposition 

 of Berthollet, they lie:ntated to pronounce more decidedly. Hence the recog- 

 nition which they evaded passed to the credit of England. Davy admitted 

 the oxygenated muriatic acid as a simple substance, giving it the name of 

 chlorine or cldorlum, but at the same time he generously resigned to his two 

 rivals the first indication of the new principle. Thus the grand theory of 

 Lavoisier was subjected to modification, though without forfeiting its title ta bo 

 considered one of the noblest contributions of French genius to science. 



The two friends, whose resources and reputation had been constatitly increas- 

 ing with their labors, had, during this whole controversy, been so completely 

 identified in effort and responsibility, that the learned abroad were disposed to 

 confound them in a single individuality ; and indeed the part borne by each 

 remains to this day undetermined. When, in 1809, a course of instruction was 

 opened at the Sorboune, both were called to participate. Here Thenard pro- 

 posed to conduct an elementary course, Avithout discontinuing, however, his more 

 abstruse labors at the College of France. So great Avas the concourse of pupils 

 that space for accommodation was often deficient, and many Avho had Avaited 

 long Avere forced to retire. This suggested to Thenard the propriety of pub- 

 lishing his lectures. They appeared accordingly in four volumes, the first 

 edition in 1813, the sixth in 1836, each edition costing much labor, as the author 

 continued to intercalate the discoveries and doctrines of successive periods. 

 This Avork maintained an exclusive ascendency in the schools for more than a 

 quarter of a century, so that it may be said that almost all Europe has learned 

 chemistry of Thenard, and doubtless most of the great chemists of the present 

 day, French or foreign, Avould take pleasure in acknoAvledging their obligations 

 to his clear and comprehensive method. 



When the Institute lost Fourcroy, numerous competitors disputed Avith 

 Thenard the honor of succeeding him. His friend Gay Lussac had the satis- 

 faction of completing, by his first vote, the unanimity of voices Avith Avhich 

 his comrade Avas called to a chair. On this occasion the first impulse of The- 

 nard Avas one Avhich sprang from his heart. " When I once felt assured of 

 success," he said, " I immediately set out for Louptiere, full of the joy Avhich 



