Henry's Chemistry. 34 



oxides toas an important fact, when M. Gay-Lussac first announced 

 it in the second volume of the Memoircs D'Arcueil. But a single 

 glance at Dr. Wollaston's scale shews that fact to be merely one 

 particular aspect of the doctrine of equivalents ; and Dr. Henry 

 should have therefore traced it to its source. The greater the pro- 

 portion of oxygen in a protoxide, the nearer does its atomic weight, 

 or equivalent, stand to the beginning of the scale, and of course, 

 the greater its saturating ratio. Thus, as 100 of lead take 7.7 of 

 oxygen to form litharge, while 100 of mercury take 4 to form the 

 black oxide, the former will take a quantity of acid compared to 

 the latter, as 7 . 7 to 4 ; for 7 . 7 : 4 : : 25 : 1 3 ; that is, the propor- 

 tions of oxygen in protoxides are uivariabiy as the atomic weights 

 of the metals ; and the less the atomic weights, the less of them is 

 requisite to saturate a given portion of any acid. 



" It has been deduced," says Dr. Henry, " by Berzelius, as a 

 general principle, from the comparison of a great number of facts, 

 that in all neutral salts, the oxygen of the acid is a multiplica- 

 tion of that of the base, by some entire number." The law he ap- 

 prehends, may be expressed more generally in the following terms : 

 When two oxidated substances enter into a neutral combination, the 

 oxygen of that which, in a galvanic circle, icould be attracted to the 

 positive pole, is a multiplication by an entire number of the oxygen 

 of that ivhich would be deposited at the negative pole. The chemical 

 associate of Mr. Dalton should have known that this is neither a 

 general principle, nor a just proposition. The particular facts in 

 unison with it, which originally misled Berzelius, are those ex- 

 hibited in the union of acids, containing two or three atoms of 

 oxygen, with bases containing only one. So fai' the thing is plain. 

 Thus sulphuric acid contains three proportions of oxygen, and 

 will hence afford a threefold multiple, (not multiplication,) of 

 oxygen, in its combinations with all the protoxides. But in some 

 of its combinations with the deutoxides, this fancied law is no 

 longer applicable, but would lead to serious errors. For in them, 

 the ratio of oxygen in the acid, is not unfrequently to that in the 

 base, as 3 to 2 or \\ to 1. Again, those acids which contain 

 two atoms of oxygen, will not, in their compounds with bases 

 also containing two atoms, give a multiple, but an equal propor- 

 tion of oxygen. Anhydrous carbonate of copper is in this predi- 

 cament. If again we consider those acids which contain only one 

 atom of oxygen, as the phosphorous, the oxygen will be either 

 a .sui-multiple of that in the bases, or equal to it in quantity, 

 according as it is combined with a deutoxidc or a protoxide. 

 This is also the case with the hyposulphites. Finally, with regard 

 to some of the nitrates, and chlorates of deutoxides, the relation 

 of oxygen in the acids, will be to that in the bases as 5 to 2. In 

 the subnitrale of copper, this relation is as 5 to 4, a proportion 

 which places in a striking ; point of view the absurdity of Berze- 

 lius's law. If wc excuse him on account of the early period when 



