CORRECTIONS FOR MOISTURE IN GAS. 49 



and specific gravities of dry and moist gases, putting M for the volume of 

 moist gas, D for that of dry gas, and V for that of vapour, all of the same 

 pressure and temperature. 



1. M=D + V. 2. ^M = D. 



.. . 



If we wish to infer the specific gravity of any dry gas from the observed 

 specific gravity or weight of the same mixed with vapour, it will be conve- 

 nient to expound p by that particular value which corresponds with a, namely, 

 thirty inches of mercury ; and let s = the specific gravity of the dry gas, and 

 w = the observed weight of 100 cubic inches of the moist gas ; then we shall 

 have the following : 



5. ^^.sa + 4 X -620 a = w. 6. s = ^ (w - 4 X '620a). 



P BO fa ^ P 



Examples. 

 1. 98 volumes of dry air + 2 volumes vapour =100 volumes of moist air. 



2. 



3. And M = V the vapour = 1 f . 



3O x 100 



4. Given D = 100, p = 30, /= '4; then 29 . 6 = 101-35 the moist 



30 x 2 



air. Given V = 2, p = 30, / = '3 ; then ^ = 200, the moist air. 



an _ .5 



5. Let/= -5, * = 1-111, a = 30-5, ^ = 29'5; then ^~^Q- Mil X30'5 



5 

 + 2^ X "62 X 30-5 = 33'64 = w, which gives the specific gravity T103. 



6. Let/, a, andjj as above, and w = 2'5 corresponding to specific gravity 



a / we \ 



0-8197 ; then . = ^f^ (*5 - ^ X '62 x 30-5) = '07266. 



The above formulae will apply equally well if V be a permanent gas, or any 

 other vapour beside that of water, the specific gravity of the gas or vapour 

 being substituted instead of '620, that of steam. 



The following is extracted from Professor Faraday's "Chemical Manipula- 

 tion," p. 381: 



H 



