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SULPHUK AND PHOSPHOECS. 



Weights of 

 the gases, 



distinctly set 

 forth. 



and their 

 numerical 

 composition. 



Other expfri- 

 jnents consi- 

 dered. 



and oxygen, and sulphuretted hydrogen and hydrogen, to 

 determine their composition. 



In the Philosophical Transactions for 1 810, page 254, I have 

 somewhat under-rated the weights of sulphuretted hydrogen 

 and -sulphureous acid gases; for I have since found, that the 

 cubical inch measures, employed for ascertaining the volumeg 

 of gas weighed, were not correct. From experiments which I 

 think may be depended upon, as the weights of the gases 

 were merely compared with those of equal volumes of common 

 air, I found that 100 cubical inches of sulphureous acid gas 

 weighed 68 grains at mean temperature and pressure, and 100 

 cubical inches of sulphuretted hydrogen 36*5 grains, and the 

 last result agrees very nearly with one given by MM. Gay 

 LussAc and Thenard, and one gained by my brother Mr. 

 John Davy. 



If 34, the weight of 100 cubical inches of oxygen gas, be 

 subtracted from 68, it will appear that sulphureous acid con- 

 sists of equal weights of sulphur and oxygen, an estimation 

 which agrees very nearly with one given by M. Berzelius ; 

 and if 227, the weight of 100 cubical inches of hydrogen be 

 subtracted from 36 5, the remainder 34'23 will be the quan- 

 tity of sulphur in the gas j and the number representing sul» 

 phur may be stated as 30; and sulphureous acid as composed 

 of one proportion of sulphur 30, and two of oxygen 30 ; and 

 sulphuretted hydrogen as composed of one proportion of sul» 

 phur, and two of hydrogen. 



From the experiments of MM. Gay Lussac, it appears that 

 sulphuric acid decomposed by heat affords one volume of oxy- 

 gene to two of sulphureous acid : from this it would appear to 

 be composed of one proportion of sulphur to three of oxygen. 

 I have endeavoured, in several trials by common heat and by 

 electricity, to combine sulphureous acid gas with oxygen, so 

 as to form a sulphuric acid free from water, but without suc- 

 cess ; and it is probable, that three portions of oxygen cannot 

 be combined with one proportion of sulphur, except by the 

 intermedium of water. Mr. Dalton has supposed, that there 

 Is a solid sulphuric acid formed by the action of sulphureous 

 acid gtis upon nitrous acid gas. But I find, that when dried 

 sulphureous acid gas and nitrous acid gas are mixed together, 

 there is no action ; but by introducing the vapour of water, 



they 



