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year 1807 he was associated with Gay-Lussac in the production of 

 the * Recherches Physico-chimiques,' which have founded their re- 

 putation in Europe, and have contributed so largely to the progress 

 of chemical science. The account of their labours appeared in two 

 volumes in 1811. The following are some of the more important 

 subjects discussed in this work. The discovery of a purely chemical 

 process of preparing in considerable quantities the metals of the 

 alkalies by decomposing potash and soda by contact with iron at a 

 high temperature, immediately after Davy had obtained them in 

 minute quantities by the action of a voltaic current ; the discovery of 

 boron, of fluoboracic acid, and of hydrofluoric acid ; researches on 

 muriatic acid and oxygenated muriatic acid, since known as hydro- 

 chloric acid and chlorine ; and lastly, a discovery which ranks 

 among those that have had the greatest influence on the progress 

 of chemistry, two methods of analysing organic compounds, with 

 an application of one of these methods to the analysis of fifteen 

 different organic substances. So highly was this work esteemed, 

 that in 1810 M. Thenard was unanimously elected Member of the 

 Institute in the place of Fourcroy. 



About this time a third Professorship was bestowed upon him, that 

 of Chemistry at the Faculte des Sciences de Paris. The discharge of 

 his new duties was followed by the same brilliant success that had 

 attended his lectures at the E'cole Polytechnique and the College de 

 France. The three Professorships which he held at the same time, 

 and the duties of which he discharged without apparent effort, 

 seemed hardly sufficient to satisfy the extraordinary activity of his 

 mind. The attractive richness of his teaching, combined with his 

 beautiful discoveries, spread his reputation over the whole scientific 

 world. It became requisite to build larger lecture-rooms for him, 

 and during twenty years he lectured to a class of more than a 

 thousand hearers. In 1812 appeared his ' Traite E'le'mentaire de 

 Chimie Theorique et Pratique.' It went through six editions, and 

 made the fortune of the publisher. This treatise, equally remark- 

 able for lucidity of exposition and completeness of matter, was 

 translated into many different languages, promoted a knowledge of 

 chemistry, and rendered the name of Thenard popular in every country 

 into which science has penetrated. 



The most remarkable of his discoveries was that of the peroxide of 



