374 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
This last result almost coincides with the first determinations with the short 
capillary M, namely 0'6192. The mean of the two results is, — 
Transpiration time of hydrosulphuric acid 0’6195 
The mercury in the gauge tube of the air-pump was soiled by these experiments, 
and the tube required to be cleaned after them. 
7 . Bisulphide of Carbon. 
At the temperature of 63°, the tension of the vapour of bisulphide of carbon was 
observed to be 10‘462 inches. Experiments were made with air, oxygen, hydrogen 
and carbonic acid gases, all saturated with the vapour of bisulphide of carbon at 63° 
and with barometer from 29’874 to 29*850 inches. The short capillary K, 8*75 inches 
in length, was made use of, and the gas was transpired into the six-pint aspirator jar. 
The gases were impregnated by the vapour in passing through a large U-shaped tube 
filled with cotton-wick which was moistened by the liquid bisulphide of carbon. 
Air alone was transpired in 982 and 98.1 seconds ; air saturated with bisulphide of 
carbon vapour in 837 and 838 seconds ; oxygen saturated with bisulphide of carbon 
vapour in 895 and 896 seconds ; hydrogen saturated with bisulphide of carbon vapour 
in 662 and 661 seconds; carbonic acid saturated with bisulphide of carbon vapour 
in 763 and 762 seconds. The ratios appear in the following Table : — 
Transpiration times of different gases saturated with CS 2 at 63°. 
Air =1. 
Oxygen =1. 
Oxvffen 
0-9124 
0-8533 
0-7769 
0-6739 
0-8212 
0-7679 
0-6992 
0-6065 
Air 
Carbonic acid 
Hydrogen 
It may be safely concluded that the transpiration time of bisulphide of carbon is 
not less than 0*6065, but probably sensibly greater. It must, according to former 
observations, approach very closely to, if it does not actually coincide with, 0*6195, 
the transpiration time of hydrosulphuric acid gas. 
8. Sulphurous Acid. 
This gas was evolved by the action of copper upon sulphuric acid, was washed 
with water, and conveyed in a continuous manner to a bottle with a relief tube from 
which the capillary was supplied, as in the experiments with ammonia and cyanogen. 
The gas was dried by passing over pumice soaked in oil of vitriol before reaching the 
capillary. 
(1.) With short capillary K, 8*75 inches in length, the six-pint aspirator-jar, and 
usual range from 2*85 to 23*5 inches : thermometer 53°, barometer 29*964 to 29*942 
inches. 
