378 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
11 . Bromine and Hydrochloric Acid. 
The only observations which I possess upon the transpiration of these two sub- 
stances were made by means of the short capillary K, of 8'75 inches in length, the 
six-pint globular receiver being the aspirator, and the fall being as usual from 28’5 
to 23*5 inches of the gauge barometer. For both the bromine and hydrochloric acid 
the bottle and relief tube were employed also as before, to regulate the supply of gas 
to the capillary. Chloride of calcium was employed to dry the gases. 
The time of air was 846, 848 seconds; of hydrochloric acid, 693, 693 seconds; of 
air saturated with the vapour of bromine at 76°, 889, 889 and 889 seconds ; of hydro- 
gen saturated with the vapour of bromine, 760, 760 seconds : thermometer from 73° 
to 76°, barometer 30 230 to 30' 178 inches. In an observation which was made at 
the same time upon the tension of bromine vapour, it was found that liquid bromine 
placed in an air-pump vacuum depressed the mercurial gauge 9T9 inches at 76°, 
which may therefore be taken as the tension of the vapour of bromine in the present 
experiments. The results are as follows : — 
Air=l. 
Oxygen=l. 
Transpiration time of hydrochloric acid gas 
Transpiration time of 9*2 vol. bromine and 21’0 vol. air 
Transpiration time of 9*2 vol. bromine and 21*0 vol. hydrogen 
0-8181 
1-0496 
0-8973 
0-7363 
0-9446 
0-8076 
It appears that the transpiration time of hydrochloric acid observed, 0‘7363, is 
greater than that of chlorine, 0'66, while that of hydrocyanic acid was found less, 
on the contrary, than that of cyanogen. 
Bromine vapour increases the transpiration time of air, and is therefore less trans- 
pirable. This vapour, however, does not appear to be greatly more transpirable than 
sulphuric acid vapour or oxygen gas. 
12. Ether {Oxide of Ethyl, Hj O). 
The ether employed was carefully washed with water, to deprive it of alcohol, and 
afterwards dried by agitation with pounded chloride of calcium. Dry hydrogen and 
other gases were impregnated with the vapour of this substance in the same manner 
as with bromine. 
(1.) The first experiments were made with the short capillary K, 8‘76 inches in 
length ; the gas being transpired as usual under the pressure of the atmosphere into 
the exhausted six-pint aspirator jar, through the range from 28’5 to 23‘5 inches of 
the gauge barometer of the air-pump : thermometer 56°, barometer 29‘670 to 
29708 inches. The tension of the ether vapour at 56° being found 12*85 inches, 
the mixture transpired may be represented as composed of 12*85 volumes ether vapour 
and 16*85 volumes gas; or of 43*26 ether vapour and 56*74 gas in 100 volumes. 
