380 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
is mixed, is widely different. It will be seen by the experiments above on ether and 
air, or ether and oxygen, that the transpiration time inclines most to the ether rate, 
while in hydrogen mixtures the time also deviates from the mean of the mixed gases, 
but greatly in the direction of the rate of the other gas, and not towards the hydro- 
gen rate. The density of a gas is no doubt an important element in this influence. 
In an experiment with the short capillary K, the time of olefiant gas was reduced 
from 0*5246 to 0*4816, by saturation with ether vapour at 60°*5. 
The rates of hydrogen and ether appear to diverge from each other in experiments 
made at a high temperature. The water in the copper trough in which the long 
capillary M was always placed, with the view of commanding a constant temperature, 
was heated to 203° (95° centig.), and preserved at that temperature during the con- 
tinuance of the following experiments. Thermometer in air 60°*5, barometer 29*956 
to 29*982 inches. 
Time of air 1634 and 1637 seconds ; of hydrogen, 798 and 797 seconds ; of hydro- 
gen saturated with ether vapour at 60°*5, 863, 863 seconds. As the gas transpired 
was measured at 60°*5 instead of 203°, the temperature at which it passed through 
the capillary, these times fall to be diminished in the proportion of the volume of air 
at 203° and at 60°*5 respectively. We thus obtain as the three mean times in which 
equal volumes were transpired at 203°, — air 1282*4 seconds, hydrogen 625*9 seconds, 
and hydrogen saturated with ether vapour at 60°*5, 677*3 seconds. 
Air=l. 
Oxygen = 1 . 
TransDiration time at 203° Fa hr. of hvdrosen 
0-4880 
0-3281 
0-4392 
0-4753 
Transpiration time at 203 of hydrogen saturated at 60°‘5 with ether vapour 
While air and hydrogen preserve, at 203°, their usual ratio of transpirability, ether 
vapour appears therefore to become sensibly less transpirable at the high temperature. 
13. Methylic Ether {Oxide of Methyl, C 2 H 3 O). 
This vapour was evolved in a continuous manner in proportion as required for 
transpiration, with the arrangements necessary for gases soluble in water. The 
vapour was passed over both hydrate of potash and chloride of calcium. The expe- 
riments were made with the short capillary K, 8*75 inches in length, like the first 
experiments with common ether. Thermometer 56°, barometer 29*650. 
Time of air 993 and 991 seconds ; of methylic ether, 532 and 532 seconds; of methylic 
ether saturated with the vapour of common ether at 56°, 508, 506 and 507 seconds. 
Transpiration times. 
Air=l. 
Oxygen =1. 
IVTethylie ether 
0-5363 
0-3111 
0-4826 
0-4600 
Methylic ether saturated with ether vapour at 56° 
