Van Mons. 397 



der life agreeable, but even' that lifeitself, by a devotion to one of 

 the noblest, if not the most esteemed, of all pursuits, the acqui- 

 sition and extension of rational knowledge, with a view to the 

 improvement and further civilization of mankind." 



Correspondence of M. Van Mons. 



[Continued from p. 316.] 



We continue with much pleasure the valuable communiaatlons 

 -of M. Van Mons. 



" M. Proust, in a recent letter to M. Delametherie, demon- 

 strates the inexactitude of several other degrees of oxidation 

 given by Thenard, Once for all, therefore, let it be understood, 

 that there are only two degrees, that of oxidule and that of oxide; 

 tiiat the ashes of the metals are combinations, by adherence, 

 when fire is employed. With respect to mercury, which is liquid, 

 trituration effects the same ; and with regard to all of them, the 

 acids resolve them into an oxidule or oxide, and into a reduced 

 metal ; and finally, that amalgamation is evident in those two 

 bodies, oxidule and oxide. The true oxidule has always the half 

 of the oxygen of the oxide, and the other relations are combi- 

 nations between those two degrees, of which the former then 

 performs the functions of oxide, and the latter the functions of 

 acid. The oxide may be hyperoxidated, and it is so almost al- 

 ways ; and as tlie hyperoxygen takes much acid from it, it can- 

 not in this state be combined with acids without depositing it ; 

 which shows that it is then insoluble in the acids of combustibles, 

 and soluble only in the acids of the burning bodies (comhuravs), 

 under tiie formation of chlorine, or of iodine : this character is 

 very striking. It is a species of salt formed l)y oxygen, like that 

 which is formed by water, by the acids, by the oxides, &c. : the 

 oxides unite it also to their own oxidules, and to oxides foreign 

 to them. Vv'e cannot analyse these combinations, but by an acid 

 aided by heat, which forms salts of them, partly in oxides and 

 partly in oxidules. When we analyse these comjiounds by means 

 of reduction, we obtain, naturally, particular appearances of 

 oxygen, which we then take for proper degrees of oxidation ; 

 then the hydrates a little intense, the hydrato-oxygenates so 

 common in the oxides of the n)etals, and the combinations be- 

 tween oxitles and oxidules, with excess of the one or the other. 

 In order that two bodies should unite, it is sufficient that one 

 shoulii l)e more burnt than the other, and that caloric should be 

 displaced. Thus there is a sub-oxidnic, or oxidation by adhe- 

 rence. These are the ashes of the metals ; next conies oxidule, 

 or first d-.'grce of oxidation, and of which some metals only are 

 •usceptible ; afterwards oxide, or second degree; and the only 

 degree for such aa are susceptiblo of one degree only ; and finally 



hyper- 



