MEMOIR OF LOUIS JACQUES THENARD. 381 



so far at least as was apparent, for the most suLtle examination had faih;cl to 

 discover the least sign of electrical action.* 



Is it due, then, to a new force'? So Thenard thought and said. The catalytic 

 force, he believed, would furnish the theoretical bond of a whole class of facts, 

 some of which were already known. As the fear of mistake is always associ- 

 ated, in a practiced mind, with the pleasure of discovery, he called to his aid the 

 counsels of a friend, a bold and sagacious chemist ; and the views of Dulong, 

 after mature consideration, coinciding with his own, he might with confidence 

 leave his conclusions to the judgment of after times. 



Thenard, associated in 1810, as professor at the Polytechnic School, with 

 the eminent men who shed so bright a lustre on that model institution, thoroughly 

 identified himself with its progress and its benefits; each generation of pupils 

 which he instructed seemed to affoi'd him a new pledge of the perpetuity of his 

 fame. In addition to this appointment, he received in 1814 that of member 

 of the Committee of Consultation for Manufactures; in 1815, he became a 

 member of the Legion of Honor; in 1821, Dean of the Faculty of Sciences; in 

 1825, he was created Baron by Charles X. Learning that he was about to 

 receive tliis latter distinction, he demanded, with visible emotion, "Why is not 

 Gay Lnssac also named? He deserves it at least as much as I do." 



At the moment he forgot, perhaps, that he had once been a courtier, and a 

 skilful one : it had been at the promptings, however, of a kind heart. Few 

 bad admired more than he those superb paintings in the cupola of the Pantheon, 

 in which the pencil of Gros has so admirably imbodied the legends of our 

 national history. The enthusiasm of his cotemporaries seemed to guarantee to 

 the artist the admiration of ages to come, when, at the expiration of only a few 

 monlhs, stains of different shapes and colors made their appearance on the 

 surface of the nave, and it became evident that, from moisture having pene- 

 trated the stones, this great work of genius was hastening to decay. The 

 mortification of Gros could be consoled neither by the public sympathy nor the real 

 concern of the sovereign, who saw with regret the threatened ruin of a moniiment, 

 in which a conspicuous place had been allotted to himself. Thenard, between 

 whom and Gros there existed a sincere friendship, no sooner heard of the 

 c»tastrophe than he commenced in secret a series of experiments, by which he 

 .was led to the discovery of a means of rendering the most porous stones imper- 

 meable to moisture. Once sure of the result, he repaired to the cabinet of the 

 artist and inquired whether he Avould repaint the cupola if satisfied that the 

 colors would stand. "A^vay with you," roughly replied Gros, "and let me 

 hear no more about it." Fourcroy, it will be remembered, had, in the words 

 of Thenard, often done the like to him, so he tranqviilly withdrew to his labor- 

 atory to await the coming of Gros. This Avas not long deferred; the door 

 presently opened and the artist inquired, in a voice of anxious emotion, if what 

 had been spoken of wei'e praciicable. That evening Thenard was summoned 

 to the Tuilleries, his method explained to the satisfaction of the royal personage, 

 Darcet at his own request was united with him, and he was dismissed with the 

 promise of a grateful requital. 



* See on this subject a very remarkable note of M. Becqnerel, Annalcs de Chimic et de 

 Ptiysifjue, t. XXVIII, p. 19, (IS'^-J), entitled: "On the electro-dynamic effects i)roduced 

 during the decomposition of oxygenated water by different bodies." The following is an ex- 

 tract: "M. Thenard discovered that the metals, with the exception of iron, tin, antimony, 

 and tellurium, tend to decompose oxygenated water ; that those which are most oxidizable 

 become oxidized, while those which are not so preserve their metallic lusturc. It has been 

 observed by M. Becquercl, that during the decomposition of oxygenated water by the sponge 

 of platinum, gold, &c., electrical effecls are produced similar to those which would take place 

 if those bodies were chemically attacked by the oxygenated water. He inferred that the de- 

 composition and the chemical action proceed from the same cause; a conclusion which 

 strongly interested M. Thenard." [See on this subject the prize essay from the Holland 

 Academj' of Sciences, published in the present Smithsonian report. ] 



