On the Ongin of the Atomic Tlieory. 409 



single step. The Doctor aclinowledges, in the number of his 

 Annals of Philosophy for December 1813, that I anticipated 

 Gay Lussac's theory of volumes : — JV/iut a loon! vet the Doctor 

 never mentioned my name in the whole history of the Atomic 

 Theory. This last circumstance shows a personal and rooted 

 prejudice. It manifests in the most decisive manner a deter- 

 mined and wilful neglect, or rather suppression of previous la- 

 bours. 



The specific gravities of the different gases, known when I first 

 wrote, were ascertained. There were very few added to them 

 since. 



The proportions in which they were capable of imiting iu 

 volumes were also knov.n. 



It was very well known that one volume of oxvgen re(juired 

 two volumes of hydrogen to constitute water ; and I had shown 

 tliat tlie one and two volumes contained the same number of 

 ultimate divisions, and that the difference of the specific gravity 

 of those gases depended on the size of their respective particles^ 

 making an allowance for the mote expanded state of the hydro- 

 gen gas. From tbis statement the weight of the atom of water 

 was rendered very obvious. 



The proportion in which oxvgen and sulphuretted hvdrogen, 

 properly prepared, united in volumes, was also given. 



It was stated, that oxygen does not contract by union with 

 sulphur in any considerable degree, so as to produce sulphurous 

 ncid,gas, and that this gas is nearly double the weight of the 

 oxvgen : hence it was inferred that an atom of snlpiuirous acid 

 consisted of one ultimate particle of oxygen, aiul an ultimate 

 particle of sulphur of tlie same weight. Tiie quantity of oxy- 

 gen consumed in saturating the sulphuretted hydrogen, gave on 

 the above principles the relative number of the particles of hy- 

 drogen and su]})hur in this compound gas. 



It was very well ascertained long since by many chemists, that 

 the gaseous oxide of azote contains one volume of azote and 

 half a volume of oxygen; and I have shown that the particles of 

 azote in this gas are united to a single particle of oxvgen; con- 

 sequently the half measure of oxvgen contains as manv divisions 

 as a full measure of azote: and as the difference of the specific 

 gravity of these gases is very small, we may infer tliat an ultimate 

 particle of azote is nearly twice as heavy as that of oxygen*. 



• The diffcrcnoe between the weiolus of an ultimate particle of azote 

 aivl oxyceii was statc-<l hy nie for the (irst time in my Atomic Theory. 

 Dr.Tliomson says, in tiie article uniler our coM!-i(ieration, that others made 

 the same remark, witliont aijufiinsi to me. It miglit be the case ; but I have 

 not bf-cn able to trace it out. 1 shall always f^ive full credit to the Doctor 

 wlien he quotes the pasia^c on ^vlsat he asserls. 



This 



