356 
PROFESSOR GRAHAM ON THE MOTION OF GASES. 
seconds ; of carbonic oxide 897, 897 seconds ; thermometer from 59° to 60°, and 
barometer from 29*1 to 29' 134 inches. These experiments give the following transpi- 
ration times : — 
Oxygen 1 
Air 0*9003 
Carbonic oxide 0*8656 
(2.) The times of air were 920 and 920 seconds ; of hydrogen 450 and 451 seconds ; 
of carbonic acid 763, 762 seconds ; thermometer 58°, barometer 29*346. The result- 
ing transpiration times for hydrogen and carbonic acid are 0*4886 and 0*8288, the 
time of air being 1 ; or multiplying by 0*9 so as to have oxygen 1 — 
Hydrogen 0*4398 
Carbonic acid 0*7459 
(3.) Experiments on the same gases were repeated at a temperature lower by 10° 
Fahr. The times of air were 902 and 902 seconds ; of hydrogen 442 and 444 seconds, 
and of carbonic acid 742 and 742 seconds ; thermometer 48° Fahr,, barometer 29*334. 
These numbers give the transpiration times 1, 0*4911, and 0*8226 for air, hydrogen 
and carbonic acid respectively; or, with oxygen as 1, — 
Hydrogen 0*4419 
Carbonic acid 0*7403 
Another series of experiments gave for carbonic acid the transpiration time 0*7432 
at 43°, and with barometer 29*620. It will be observed that the time for carbonic 
acid now begins to rise, as if the capillary were too short and the resistance insuffi- 
cient to neutralize entirely the effect of effusion in that gas. The times however of 
air, hydrogen and carbonic oxide continue normal. 
Experiments were made with the same capillary reduced to 6*4375 inches, or to 
one-eighth of its original length, which are still pretty normal. The times for air 
were 670 and 670 seconds ; for oxygen 746 and 745 seconds ; for hydrogen 322 and 
322 seconds; for carbonic acid 563 and 562 seconds, with thermometer from 61° to 
62°, and barometer from 29*832 to 29*826. These give the transpiration ratios, — 
Oxygen 1 
Air 0*8987 
Hydrogen 0*4319 
Carbonic acid 0*7545 
For shorter lengths of the capillary K, the deviation from the transpiration rates 
becomes very notable. I shall supply the results of such experiments, as they illus- 
trate the progress of the deviation from the transpiration rates in a short and narrow 
capillary, while the results of Table II. page 352, show the progress of this deviation 
in a long and comparatively wide capillary. 
