[ ^^7 ] 



at a medium 62,5. 100 grains of alkaline air weigh 18,16 grains, 

 as I have (hewn in a former treatife, barometer 30, thermometer 

 61. Then at that barometrical height 129 cubic inches would be- 

 come 130; but as the heat in the prefent experiment exceeded 61, 

 the expanfion refulting from it muft be fubftraded ; and according 

 to Mr. Morveau, 2 An. Chy. a volume of this air at 32° being 

 taken as i becomes at 77° 1,2791, and confequently gains 0,0062 

 by each intermediate degree, confequently the volume of this 

 would at 61 be only 129,1 ; its weight therefore is nearly 24 

 grains. This fait contained 52 percent, of fixed air, confequently 

 its ingredients were 52 grains fixed air, 24 of mere alkali, and 

 24 of water. 



The proportion of vol-alkali in aerated vol-alkalis vary, increafing 

 or decreafing with the proportion of fixed air they contain. 



Mr. Cavendish in the Philofophical Tranf. for 1766, p. 169. 

 found that 1643 grains of aerated vol-alkali, containing 53,8 per- 

 cent, of fixed air, faturated the fame quantity of marine acid as 

 1680 of another parcel, which contained but 52,8 per cent, of 

 fixed air. 



Hence the quantities of mere alkali in each were reciprocally as 

 1680 to 1643, and thefe are nearly to each other as 53,8 to 52,8; 

 and as the aerated vol-alkali that contained 52,8 per cent, of fixed 

 air contained 24 per cent, of mere vol-alkali ; that which contained 

 53,8 per cent, of fixed air fhould have contained 24,83 per cent. 



L 1 2 Hence 



