1814.] Higgins on the Atomic Theory, &c. 61 



which in my experiments I found to be the case : 100 measures of 

 sulphureted hydrogen gas require for complete combustion 150 

 measures of oxygen : 50 of these will combine with hydrogen and 

 form water, and 100 will combine with sulphur and form sulphurous 

 acid. The sulphurous acid formed will, 1 believe, occupy exactly 

 100 measures. 



Mr. Higgins has made us acquainted with some new facts respect- 

 ing sulphurated hydrogen gas, the most important of which is its 

 solubility in ether. 



I come now to Mr. Higgins' Appendix, which is so curious a 

 production that I cannot avoid laying it entire before my readers. 

 It is as follows : — 



" Since writing the foregoing pages, an extract, taken from a 

 very ingenious essay on the cause of chemical proportions, written 

 by Berzelius, Professur of Chemistry at Stockholm, appeared in a 

 periodical work, called AnnaU of Philosophy, &c. (for December, 

 1813,) of which Dr. Thomson, it seems, is the editor. The cele- 

 brated author of this essay makes the following remarks on the 

 atomic system : — 



" ' When we reflect on this cause, it is first evident that it must be 

 of a mechanical nature; and what presents itself as the most pro- 

 bable idea, most conformable to our experience, is that bodies are 

 composed of atoms or of molecules, which combine one with one, 

 one with two, or three, four, &c. : and the laws of chemical pro- 

 portions seem to result from this with such clearness and evidence, 

 that it seems very singular that an idea so simple and probable has 

 not only not been adopted, but not even proposed before our own 

 days. 



" ' As far as I know, the English philosopher, Mr. John Dalton, 

 guided by the experiments of Bergman, Richter, VVenzel, Ber- 

 thollet, Proust, and others, was the first person who endeavoured to 

 establish that hypothesis.' " 



t>ir Humphry Davy has lately assured us that Mr. Higgins, in a 

 book, published in 17^9, established the same hypothesis. I have 

 not seen the work of Mr. Higgins, and can only notice the circum- 

 stance on the authority of Davy. 



" Here follows Dr. Thomson's remarks on this passage, in a 

 note at the foot of the page." 



' The work of Higgins on phlogiston is certainly possessed of 

 much merit; and anticipated some of the most striking subsequent 

 discoveries ; but when he wrote metallic oxides were so little 

 known, and so few exact analyses existed, that it was not possible to 

 be acquainted with the grand fact that oxygen, &c. always unite in 

 determinate proportions, which are multiples of the minimum pro- 

 portion. The atomic theory was taught by Bergman, Cullen, Black, 

 &c. just as far as it was by Higgins. The latter, indeed, states 

 some striking facts respecting the gases, and anticipated Gay- 

 Li^sac's theory of volumes; but Mr. Dalton first generalized the 

 doctrine, and thought of determining the weight of the atoms of 



