and Thenard made a fundamental contribution to the realization that so-called oxymuriatic acid contained no oxygen and was an element ...
This was not quite the truth that Gay-Lussac
had had in mind, or the truth that the early photographers of war had gone out to shoot.
While most seems passive and we, outsiders, are looking in, time and its passage become clear-cut; properties and houses, and people, exteriors and interiors, change - and so too does the reader, inside after all, moved by Gay-Lussac
's masterly book.
In 1832, Gay-Lussac
 succinctly summarized Berthollet's work on reactions and chemical compounds as follows "Berthollet avait raison propos des reactions, elles produisent en general un equilibre entre constituants, qui depend des conditions de reaction; il avait tort en ce qui concerne les composes produits".
Whereas Lavoisier had burned a few inflammable substances, using mercuric oxide as the source of oxygen, Joseph Louis Gay-Lussac
(1778-1850) and Louis Jacques Thenard (1777-1857) revolutionized organic analysis in 1810 by adopting an oxidizing agent, potassium chlorate.
The striking versatility of Berthelot coupled with his remarkable drive brings to mind the earlier impressive exploits of his celebrated compatriot Joseph Louis Gay-Lussac
(1778-1849) that were also characterized by wide variety and great quantity .
He was named professor of organic chemistry at Ecole de Medecine in 1829, and three years later was appointed Assistant Professor at the Sorbonne, where he was to succeed the famous Joseph Louis Gay-Lussac
in 1841 .
Joseph Louis Gay-Lussac
is well-known for his discovery of the law of combining gas volumes which was published in 1809 in a paper entitled "Sur la combinaison des substances gazeuses, les unes avec les autres" .