PROFESSOR GRAHAM ON THE MOTION OF GASES. 
367 
numbers which are as 1 to 0‘5830. The ratios or transpiration times appear in the 
following- Table ; — 
Transpiration times of Olefiant Gas. 
Air = 1. 
Oxygen = 1. 
From 20 to 10 inches ... 
From 10 to 6 inches ... 
From 6 to 4 inches ... 
From 4 to 2 inches ... 
From 2 to 1 inch 
0-5830 
0-5709 
0-5667 
0-5679 
0-5656 
0-5212 
0-5103 
0-5066 
0-5085 
0-5081 
In reducing these results from the scale of air to that of oxygen, the following 
coefficients were used as the transpiration times of air. They were obtained by 
experiment. From 20 to 10 inches air =0'8941 ; from 10 to 6 inches 0'8939 ; from 
6 to 4 inches 0*8941 ; from 4 to 2 inches 0*8967 ; from 2 to 1 inch 0*8967 ; the air 
coefficients being all sensibly lower than 0*9. 
The transpiration time of this gas appears to vary at different parts of the scale of 
pressure fully more than carbonic acid does. This may arise, as with carbonic acid, 
from the extreme difference which exists between the effusion and transpiration rate 
of the gas. 
Hence an unusually great resistance, which is only met in the lower part of the 
scale, is required to eliminate completely the influence of effusion upon the transpira- 
tion rate. The smallest transpiration time observed above for olefiant gas is 0*5066, 
which certainly does not differ much from 0*5, or half the time of oxygen. But it 
would be premature to adopt that relation definitively, as a number nearer to 0*51 
would be the more legitimate expression of the whole results. 
In a second series of experiments conducted precisely in the same manner, with 
the thermometer at 67° and the barometer 30*020 to 30*034, the results were as 
follows : — 
Transpiration time of Olefiant Gas (into air). 
Air =1. 
Oxygen =1. 
From 20 to 10 inches ... 
From 8 to 6 inches ... 
From 6 to 4 inches ... 
From 4 to 2 inches ... 
From 2 to 1 inch 
0-5855 
0-5745 
0-5663 
0-5642 
0-5647 
0-5234 
0-5136 
0-5062 
0-5043 
0-5048 
From 20 to 1 inch 
0-5669 
0-5068 
The same remarks apply to the last as to the immediately preceding series of ex- 
periments ; the two series agreeing together most closely. The mean of the three 
times observed in the range of pressure from 6 inches to 1 inch is 0*5051 ; and the 
least transpiration time observed for olefiant gas (from 4 to 2 inches pressure) is 
0*5043. 
3 B 2 
