PROFESSOR GRAHAM ON THE MOTION OF GASES. 
577 
The effusion-rate of this gas approaches therefore very closely to the theoretical 
number. In the calculations the density of carbonic oxide is taken at 0-96779, as 
found by Wrede. 
Carburetted Hydrogen., CH 2 . — This was the gas of the acetates, prepared by heat- 
ing a mixture of acetate of soda with dry hydrate of potash and lime. 
The temperature of the gases effused being 59°-5, and the exhaustion 29'3 inches; 
the constant volume of air passed through the aperture in 493 seconds, of carburetted 
hydrogen in 373 seconds : 
Time, air =1. 
Theoretical time. 
Velocity. 
Theoretical 
velocity. 
Carburetted hydrogen 
0-756 
0-7449 
1-322 
1-3424 
The density of carburetted hydrogen is taken at 0-5549 in the calculations. 
Carbonic Acid and Nitrous Oxide. — In the first experiment with carbonic acid, the 
gasometer with the gas was floated as usual over water; thermometer 58°‘5. The 
effusion of air took place in 495 seconds, of carbonic acid in 595 seconds. To dimi- 
nish the loss of the latter gas occasioned by its solubility in water, a second experiment 
was made over brine: the time required by the carbonic acid was now 603 seconds. 
The velocity of effusion of carbonic acid is by the first experiment 0-832 ; by the 
second it approaches more nearly the theoretical number, calculated from T52901 
(Regnault) as the density of this gas, as appears below : 
Time, air =1. 
Theoretical time. 
Velocity. 
Theoretical 
velocity. 
Carbonic acid 
1-218 
1-2365 
0-821 
0-8087 
The observation on nitrous oxide was made on a different occasion, with a tempe- 
rature of 62°-5. The time of effusion of air was then 488 seconds ; of nitrous oxide 
585 seconds, the gas being collected over water : 
Time, air = 1. 
Theoretical time. 
Velocity. 
Theoretical 
velocity. 
Nitrous oxide 
1-199 
1-2365 
0-834 
0-8087 
The specific gravity of nitrous oxide is assumed in the calculations to be the same 
as that of carbonic acid. The time of effusion of both of these gases is shortened by 
the loss of a portion of the gas, by solution in the water of the pneumatic trough 
during the period of the experiment, and falls below the theoretical number. In 
carbonic acid over brine, where the injury is least from this cause, the observed velo- 
city is, however, still within one-seventieth part of that calculated from the specific 
gravity of the gas. 
MDCCCXLVI. 4 F 
