352 Analysis of Scientific Books. 



concerning Sir H. Davy and the atomic theory; and we are 

 Avarranted in affirming, that his account of the matter is alto- 

 gether false. Sir H. Davy has never embraced the atomic 

 theory as taught by Mr. Dalton, or as expounded by the Regius 

 Professor. With the first and great part of the doctrine of che- 

 mical proportions, that of reciprocal saturation of acids, bases, 

 and salts, Sir H. was acquainted long before Mr. Dalton 

 broached it. It was clearly taughf by Richter; and a fine ex- 

 ample of it is to be found in the Chemical Researches 

 on Nitrous Oxide, bearing date, .Tune 25, 1800. We know, at 

 the present day, of no single specimen of chemical equivalents 

 bletter developed than the following: " Hence," says Sir H., 

 " we gain the following equation : — 

 "6.5 green sulph. of iron:iz 2.41 sulph. acid+ 4.1 gr. ox. iron. 



1.44 nitrous gas =0.64 nitrogen -|- .8 oxygen. 



1.0 water r: 0.85 oxygen + 0.15 hydrogen. 



Equal, 

 3.2 sulph. ammon. =2.41 sulph. acid + 0.64 nitrog. + 0. 15 hydr. 

 5.7 red ox. iron =4.1 gr. ox. iron + 1.6 oxygen t." 



Was the author of this equation, and of a multitude of similar 

 researches, published so early as 1800, to get his first glimpse of 

 the atomic theory, as Thomson miscalls it, or of the theory of 

 reciprocal proportions, from any long conversation with Dr. 

 Thomson, in 1807 ? How dare the Dr. say, therefore, " 1 knew 

 from Davy himself that he had no idea whatever of definite pro- 

 portions till Mr. Dalton had made known the outlines of his 

 theory*." Mr. Dalton, through the courtesy of Sir H. Davy and 

 his friends, was brought forward to lecture in the R. I. in 1803 ; 

 at which time this ingenious observer thought he saw in Sir H. 

 Davy's researches on the compounds of azote and oxygen, indi- 

 cations of multiple proportions, an idea manifestly thrown out 

 and abandoned to the world by Mr. Higgins, a few years before. 

 Sir H. Davy, with that integrity of intellect and attachment to 

 the Baconian logic, which distinguishes all his inquiries, thought 

 that Mr. Dalton strained experimental results to suit his theo- 

 retical opinions, and therefore hesitated to adopt the second 

 part of what is now called the atomic theory, namely, the doc- 

 trine of multiple proportions, till experiments should demon- 

 strate its truth. Mr. Dalton persevered most laudably to 

 make out, by an extensive induction of facts, the justness 

 of these views ; which received their final confirmation from 

 Dr. Wollaston's paper on the super-oxalic and sub-oxalic salts, 

 and M. Gay-Lussac's beautiful memoir on gaseous volumes. 

 At present, the theory of reciprocal and multiple proportions, 

 as taught in SirH. Davy's Elements of 1812, is undoubtedly a 

 much truer representation of chemical principles than any thing 



* Researches concerning nitrous oxide, p. 172. 

 + Answ;r, p. 254. 



