376 W. Gibbs : Contributions to Chemistry. 
Art. XLIV.—Oontributions to Chemistry from the Laboratory of 
the Lawrence Scientific School. No. 11; by Wotcorr Grsss, 
M.D., Rumford Professor in Harvard University. 
1. Ona simple method of avoiding observations of temperature 
and pressure in gas analyses.* 
from its volume at the temperature ¢ and pressure p by the famil- 
lar expression : 
1 h-h'-h’ 
reas. 1+4-0°00367¢° 760 (1) 
in which h is the observed height of the barometer (reduced to 
0° C.), h’ the tension of the vapor of water at ¢° when the gas is 
moist and h” the height of the column of mercury in the col- 
lecting tube above the level of the mercury in the cistern. For 
any other gas under precisely the same circumstances of tempe!- 
ature and pressure we have the equation: 
, ; 1 h-h'-h" 
Vo=Vs Teen ye 
Whence dividing the first equation by the second we have: 
Oo— "1 
vi, v7, (8) 
or as a proportion eae tie ee (4) 
from which it appears that the reduced volume (vol. at 0° and 
7 of the second gas may be found without observations of 
emperature and pr , provided tht the unreduced volume 
be Shecrved under the same ci stances of temperature and 
_ _Inlike manner we shall have for the weight of the gas et 
_ Measured w,V%,, and since the weights do not change with 
| e and have finally : 
em peTrahin 
wV,:w0,V'::0V,:0,V',. 
W we suppose that the gas in the first tube, or standard 
Read before the National Academy of Sciences, Sept., 1869. 
