On the Atomic Theory. 1(>3 



The numbers alone would avail nothing, if they had not been 

 coupled with the proportions of particles which constituted dif- 

 ferent compounds, and vice versa ; and the language expressive 

 of those ideas runs uniformly and conspicuously throughout my 

 whole work. 



" After concluding that it is unnecessary to admit the ex- 

 istence of the imaginarv substance, plilogiston, in sul})hur, he 

 concludes, in page 36, that sulphurous acid is compounded of one 

 ultimate particle of sulphur with one of oxygen, and that sul- 

 phuric acid consists of one of sulphur and two of oxygen. 



" In the same page he also observes, that water is formed of 

 one ultimate particle of water* united to one of oxygen." 



The author next quotes my statement of the constituents of 

 sulphuretted hydrogen, and the porportions which their respec- 

 tive particles bear to each other, and then passes to my estimate 

 of the proportions of the particles of azote and oxygen in nitrous 

 oxide, nitrous air, red nitrous acid, straw-coloured nitrous acid, 

 and in the nitric acid. 



*^ These facts," continues he, "are certainly very remarkable, 

 as they agree with the conclusions in the present time, and give 

 a strong proof of Mr. Higgins's genius at t^ie time he wrote, 



" He does not, however, lay any stress u|)on these remarks, 

 and was not probably aware that thev would be confirmed by 

 future research." 1 was perfectly satisfied that I was rii;ht, and 

 that my demonstrations would bear the test of time and investi- 

 gation f; and the best stress I could set upon them wa*^, to lay 

 them before the public. But he goes on : " We are induced to 

 think so from the manner in which he expresses himself in othtr 

 parts of his work, in which he frequently speaks of the absorp- 

 tion of small portions of oxygen, and of bodies having a small 

 portion of oxygen more than they can retain." 



These remarks do not in the smallest degree invalidate the 

 principles which I advanced. We know that distilled w„ter 

 absorbs oxygen from the atmosphere, that all the sulphites gra- 

 dually absorb oxygen from the atmosphere, so as, in time, to be- 

 come sulphates. And many substances contain more oxygon 

 than they can well retain ; — instance, nitric acid, euchlorine, 

 oxymuriate of potash, and the oxides of gold and silver, parti- 

 cularly the latter. 



" This vague manner of speaking, and others which we do 

 not immediately recollect, is sufficient to show that Mr. Higgins 

 had no fixed notions of the cause of definite proportions; and the 

 language in which he has used ultimate particles and molecules, 



• The author made a mistake ; read a particle of hydrogen instead of a 

 particle o water, 

 t See preface to my Comparative View. 



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