TAKING THE DENSITY OF VAPOUR OF VOLATILE LIQUIDS. 463 
were made using nitrogen gas as the diluent. The gas had been prepared by 
burning phosphorus in air, collected in a gasholder, and finally passed through 
a strong solution of pyrogallate of potash, and dried with sulphuric acid :— 
le 
Vapour-density determination at 97-5° C. 
Cubic Cent. at 0° C, 


Grm. 
and 760 m. m, 
Vol. of N+ NO, 26397 weighing 4473 
REN Wan 15947 . 2063 
104-50 -2410 
Therefore 10450 C. C. of NO, weigh ‘2410 grm. Vapour density = 1°783. 
Dilute solution of potash (sp. gr. 1:0043) was used to absorb the peroxide of 
nitrogen. The residual nitrogen was then calculated as being quite saturated 
with moisture, for potash of so low a specific gravity would not sensibly differ 
from pure water in point of tension. , 
In this and the following experiments it was carefully ascertained that the 
residual nitrogen was quite colourless: also, on making repeated experiments, no 
coloration could ever be seen on admitting air to the residual gas. 
II. 
Vapour-density determination at 24:5° C. 
Cubic Cent. at 0° C. 


Grm. 
and 760 m. m. 
Vol. of N+ NO, 425:29 weighing ‘8963 
morale "te. 244:39 * -3070 
180:90 5893 
Therefore 180-90 C. C. of NO, weigh ‘5893 grm. Vapour-density = 2°52. 
The absorption of NO, was made by means of water. 
Tit, 
Vapour-density determination at 113° C. 
Cubic Cent. at 0° C. 


Grm. 
and 760 m. m. 
Vol. of N+ NO, 4.49°05 weighing “7556 
eT Fie 349-4 : 4390 
92°65 -3166 
Therefore 92°65 cub. cent. of NO, weigh ‘3166 grm. Vapour density = 2°645. 
In this determination strong caustic soda (sp. gr. 1°348) was used to absorb the 
NO,. In making the calculation the gas in contact with such a solution was con- 
sidered half dry. By this means absolute precision is sacrificed to certainty. 
It cannot be doubted that the strong alkali would completely absorb all NO, 
without evolving NO,. 
