0?i Chemical Lfjuivaltids . 109 



oxidation of all the rest. Since the peroxides require most acid, 

 we can easily understand how the salts containing- them, should 

 be in general more soluble than those with the protoxide. 



M. Gay-Lussac concludes his memoir with this observation : 

 AVhen we precipitate a metallic solution, by sulphuretted hydro- 

 gen, either alone or combined with an alkaline base, we obtain a 

 sulphuret or a metallic hydrosulphuret. In the first case, the hy- 

 drogen of the sulphuretted hydrogen combines with all the oxy- 

 gen of the oxide, and the suljjhur forms a sulphuret with the me- 

 tal ; in the second case, the sulphuretted hydrogen combines di- 

 rectly with the oxide, without being decomposed, and its pro- 

 portion is such, that there is sufficient hydrogen to sifturate all 

 the oxygen of the oxide. The quantity of hydrogen neutralized, 

 or capable of being so, depends therefore on the oxidation of the 

 metal, as well as the quantity of the sulphur which can com- 

 bine with it. Of consequence, the same metal forms as many 

 distinct sulphurets, as it is susceptible of distinct stages of oxida- 

 tion in its acid solutions. And as these degrees of oxidation are 

 fixed, we may also obtain sulphurets, of definite proportions, 

 which we can easily determine, according to the quantity of oxy- 

 gen to each metal, and the proportions of sulphuretted hydro- 

 gen. 



The next chemist who contributed essentially to the improve- 

 ment of the equivalent ratios of chemical bodies, was Berzelius. 

 By an astonishing number of analyses, executed for the most; 

 part with remarkable precision, he enabled chemical philosophers 

 to fix with corresponding accuracy, the equivalent ratios reduced 

 to their lowest terms. He himself took oxygen as the unit of 

 proportion. 



The results of all this emulous cultivation, were combined and 

 illustrated with original researches, by Sir H. Davy, in his Ele- 

 ments of Chemical Philosophy published in 1812. In this sys- 

 tem of truths, which will never become obsolete, we find the 

 claims of Mr. Iliggins to the discovery of the atomic theory justly 

 advocated. 



But what peculiarly characterizes this chemical work, is the 

 sound antihvpothetical doctrines which it inculcates on chemical 

 combination. " Mr. Miggius," says Sir II., " has supposed that 

 water is composed of one particle of oxygen and one ot hydro- 

 gen, and Mr. Dalton of an atom each : but in the doctrine of 

 proportions derived from facts, it is not necessary to consider 

 the combining bodies, either as composed of indivisible particles, 

 or even as always united, one and one, or one and two, or one 

 and three |)roportions. Cases will be hereafter pointed out, in 

 which the ratios arc very difTcrcnt; and at present, as we iiavc 

 no means whatever of judging either of the relative numbers, 



figures, 



