PROFESSOR GRAHAM ON THE MOTION OF GASES. 
379 
The time of air was 988, 988 seconds ; of hydrogen 474, 473 seconds ; of hydrogen 
gas saturated with ether vapour at 56°, 498, 500 seconds ; of oxygen gas saturated 
with ether vapour at the same temperature, 696 and 695 seconds. The transpiration 
times deducible from these observations are, — 
Air=l. 
Oxygen = 1, 
Transpiration time of hydrogen 
Transpiration time of ether vapour and hydrogen 
Transpiration time of ether vapour and oxygen 
0-4792 
0-5051 
0-7040 
0-4.312 
0-4546 
0-6336 
It thus appears that the transpiration time of hydrogen, 0-4312, is only increased to 
0*4546 by 43-26 per cent, of ether vapour. As the influence of hydrogen upon the rate 
of transpiration of the dense gases and vapours is scarcely sensible, this may be held 
as proving that the time of ether vapour does not sensibly exceed the time of the 
hydrogen mixture, 0*4546. But as the experiment has been made with a capillary of 
small resistance, it is not impossible that the normal time of ether vapour may be 
still sensibly less. 
(2.) The capillary M, 52*5 inches in length, with the two-pint aspirator, was now 
used, the other arrangements remaining as before : thermometer 68°*5 to 69°, baro- 
meter 30*242 to 30*264 inches. 
The time of air was 1084, 1084 seconds ; of air saturated with ether at 68°*5 (59*5 
ether vapour to 40*5 air), 675, 676 and 673 seconds ; of hydrogen saturated with ether 
vapour at 68°*5 (59*5 ether vapour to 40 5 hydrogen), 533, 529 and 531 seconds ; of 
oxygen saturated with ether vapour at 68°*5 (59*5 ether vapour to 40*5 oxygen), 728, 
725 and 727 seconds ; of hydrogen alone, 529, 529 seconds. The tension of ether 
vapour was observed at the time to be 17’95 inches at 69°. The results deduced from 
these experiments are as follows : — 
Air= 1. 
Oxygen = 1. 
Transpiration time of ether vapour and air 
0-6224 
0-4898 
0-6771 
0-4880 
0-5601 
0-4408 
0-6039 
0-4392 
Transpiration time of 59*5 ether vapour and 40-5 hydrogen ... 
Transpiration time of 59*5 ether vapour and 40-5 oxygen 
Transpiration time of hydrogen 
In this capillary of great resistance, the time of hydrogen is therefore not sensibly 
affected by nearly one and a halftimes its volume of ether vapour, from which it may 
be inferred that the transpiration time of ether vapour itself does not diverge sensibly 
from that of hydrogen. The near if not perfect coincidence in transpirability in these 
two substances is very remarkable, considering their great dissimilarity in physical 
characters, particularly in weight, the densities of hydrogen and ether vapour being 
as 1 to 37 . 
Although hydrogen and ether may have the same transpirability, still the influence 
which each of these gases exerts upon the transpiration of other gases with which it 
