2Q . .CONSTITUTION OF MIXED GASES. 



VI. 



Farther Ob/Ovations on the Conjlitution of mixed Gafes. In a 

 Lelte r from Mr. John Gough. 



To Mr. NICHOLSON. 

 SIR, 



O 



An apology for VJ'THER philofophers, befides Mr. Dalton, have maintained 

 this letter. ^ e ex ;ft ence f f ree elaftic vapour in the atmofphere; but as 



the modification given by this gentleman to the opinion, is 

 perhaps the laft it will receive, I am defirous of trefpafling 

 once more on your pages, in reply to my opponent, a,s well 

 as to (hew the changes which the prefent controverfy has pro- 

 duced in his fyftem. 

 Some objections Mr. Dallon's laft letter begins by expofing my ignorance of 

 confidcred. *' chemiftry, and difapproving the data, by help of which air 

 has been (hewn to be a chemical compound. Although his 

 fufpicions may be juft in many inftances, they are wrong in 

 this ; for the facts fiated by Mr. D. were known to me at the 

 time of writing that paper; and the reprobated data were 

 adopted for the following reafons : 

 Specific gravity Mr. Davy found the weight of 100 cubic inches of oxigen- 

 oi^oxigenous ous gas> f" t he temperature of 50°, to be 35. 06 grains, the 

 v barometer (landing at 30 inches : now the denfities of the fame 

 elaftic fluid at 50 Q and 60°, are in the ratio of 105824 to 

 103744*: but when the magnitude is given, i. e. 100 parts, 

 the weights are as the denfities ; confequently the weight of 

 100 cubic inches of ovigenous gas at 60°, is 34.37 grains, 

 the barometer (landing at 30: but 31 grains being the weight 

 of an equal bulk of air in like circumftances, and its fpecific 

 gravity being denoted by 1000, the correfponding fpecific gra-. 

 . vity of oxigenous gas is expreffed by the number 1108 ; which 

 exceeds Mr. Kirwan's expreffion only by five. This approx- 

 imation to an exact coincidence, aTfords the ftrongeft evidence 

 of the correclnefs both of Mr. Kirwan and Mr. Davy, that 

 can be expected in a queftion of the kind ; and, as (he former 

 gentleman made ufe of the fame apparatus to determine the 

 weight of air which had loft its oxigen by being expofed to 



* Thomfon's Chemiftry, Vol. I. p. 342. 



the 



