31 
oxygen ; but he argues very justly that the merit consisted in the 
far-seeing power which could divine the existence of a definite com- 
bination of oxygen and hydrogen, essentially distinct from ordinary 
water. 
M. Thenard had the good fortune to labour in conjunction with a 
host of great men — with Fourcroy, with Dulong, with Biot, with 
Dupuytren, but, above all, with Gay-Lussac. It is in this last con- 
nection, I imagine, that his name comes most frequently under the 
eye of non-chemical readers amongst us. Gay-Lussac and Thenard 
published, in conjunction, a series of most valuable memoirs, which 
were afterwards united in two volumes. Of these volumes Berthol- 
let thus speaks : “ They seem to constitute a new science, raised on 
the old sciences of physics and chemistry as their groundwork.” 
Amongst the vast mass of discoveries which these researches make 
known, I have space to mention only two : 1. A highly important 
series of facts tending to throw light on the relation between the 
chemical and the electrical energy of the voltaic pile. For example, 
that acidulated water, as compared with pure water, increases the 
chemical action of the pile, but diminishes the electrical ; and that 
those fluids which were found most efficient in exciting the chemi- 
cal powers of the battery are the most rapidly decomposed when 
subjected themselves to its action. 2. The indication of the means 
of obtaining considerable quantities of potassium and sodium, by 
subjecting caustic potash and soda to the contact of iron at a high 
temperature ; and the train of consequences which flowed from the 
facility of producing those metals. The Memoir which contains 
the process referred to appeared in the Moniteur of the 15th and 
16th November 1808. In it was announced the existence of a 
particular radical, boron, which Davy described a month later in a 
valuable paper read to the Boyal Society of London. 
Not the least important, however, of M. Thenard’s publications 
was his Traite de Chimie , which has gone through six editions. He 
had a happy talent for popularizing, without the sacrifice of strict 
scientific accuracy. His genius lay in arranging the parts, in deve- 
loping truths in succession, in bringing out the characteristic facts, 
and causing the whole science to rest symmetrically on them. And 
the same power of popularizing and arranging was observable in his 
lectures. The courses which he delivered at the Athenaeum, at the 
