364 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
Transpiration time of Carbonic Oxide. 
From 20 to 10 inches 0'8727 
From 10 to 6 inches 0’8755 
From 6 to 4 inches 0*87 15 
From 20 to 4 inches 0‘8737 
The transpiration time of carbonic oxide thus appears to be uniform at different 
pressures, and to correspond very closely with its theoretical density, 0‘8750. The 
transpiration times of this gas and of nitrogen no doubt correspond with each other 
as closely as their densities, and are both double the time of hydrogen. 
It thus appears that the results obtained by means of the sheaf of capillaries of 
extreme resistance are the most uniform of all, and that they afford a confirmation of 
the conclusions drawn from the results of former capillaries of greatly less resistance, 
which it is difficult to withstand. These conclusions are, that the times of passage 
through capillary tubes, of equal volumes of different gases under the same pressure, 
approximate to, and have their limit in, the following numbers : — 
Transpiration times. 
Oxygen 1‘ 
Air 0‘9010 
Nitrogen and carbonic oxide . . . 0’8750 
Hydrogen 0'4375 
Carbonic acid 0‘7272 
The times of oxygen, nitrogen, carbonic oxide and air, are directly as their densi- 
ties, or equal weights of these gases pass in equal times. Hydrogen passes in half the 
time of nitrogen, or twice as rapidly for equal volumes. The result for carbonic acid 
appears at first anomalous. It is, that the transpiration time of this gas is inversely 
proportional to its density, when compared with oxygen. It is to be remembered, 
however, that carbonic acid is a compound gas, containing an equal volume of oxygen. 
The second constituent carbon which increases the weight of the gas, appears to give 
additional velocity to the oxygen in the same manner and to the same extent as 
increased density from pressure, or from cold (as I believe I shall be able to show), 
increases the transpiration velocity of pure oxygen itself. A result of this kind shows 
at once the important chemical bearing of gaseous transpirability, and that it emulates 
a place in science with the doetrines of gaseous densities and combining volumes. 
The circumstance that the transpiration time of hydrogen is one-half of that of nitro- 
gen, indieates that the relations of transpirability are even more simple in their ex- 
pression than the relations of density among gases. In support of the same assertion 
may be addueed the additional fact, that binoxide of nitrogen, although differing in 
density, appears to have the same transpiration time as nitrogen. Protoxide of 
nitrogen and carbonic acid have one transpiration time, so have nitrogen and 
carbonic oxide, as each pair has a common density. 
