PROFESSOR GRAHAM ON THE MOTION OF GASES. 
587 
The principal results of the preceding- table, and also the results of two series of 
experiments or mixtures of hydrogen with carburetted hydrogen (C II 2 ) and with 
carbonic acid, are exhibited by means of the curves projected in Plate XXXIV, for 
the purpose of comparing with them the results of the transpiration of the same 
mixtures exhibited in Plate XXXV, which I have not yet succeeded in reconciling 
with any physical law. Feb. 1846.] 
The numbers at the top and bottom of the Plate, which apply to the vertical lines, 
express the times of effusion, the time of oxygen being taken as 100 ; while the num- 
bers to the right of the table, and which apply to the horizontal lines, express the 
volumes of hydrogen in 100 volumes of the mixture. Thus the curves all terminate 
above in a common point, 26 - 3, the time of 100 hydrogen ; and each terminates below 
with the proper time of the particular gas which is mixed with hydrogen, the propor- 
tion of hydrogen being then 0, and that of the other gas 100 ; that is, the curve of the 
carburetted hydrogen mixtures at 72‘32 ; the curve of the nitrogen mixtures at 93'5 ; 
that of the air mixtures at 95T ; that of the oxygen mixtures at 100, and that of the 
carbonic acid mixtures at 116. 
/. Effusion of Air of different Elasticities or Densities, by brass plate B. 
In all the experiments hitherto described, the air or gas effused was under the 
atmospheric pressure, which varied only within narrow limits. It was desirable to 
know whether the time remained constant for the passage into a vacuum of equal 
volumes of air of all densities, which the theory of the passage of fluids into a vacuum 
requires. 
The air was drawn into the receiver of an air-pump (fig. 2. Plate XXXIII.), main- 
tained vacuous by continued pumping, from the globular gas receiver a, placed in a 
deep glass basin half-filled with water and used as a pneumatic trough ; this basin 
and the globular vessel being placed on the plate of a second air-pump under a 
large bell -jar in which a partial exhaustion could be maintained during the conti- 
nuance of the experiment. The vessel a had tubular openings at top and bottom ; 
its capacity between the marks b and c in these necks was 65 cubic inches ; the lower 
tube was expanded under the mark b into an open funnel ; the upper tube was cylin- 
drical with a flange or lip, and had a sound cork fitted into it. A short brass tube d, 
of quill size, soldered to the end of the stopcock e, descended into the bell-jar and 
passed through the cork of a, which was perforated. The vessel a having thus an 
air-tight communication with the exhausted receiver v of the first air-pump, by the 
tube F, the drying tube U and the tube H ; a measured quantity of air (65 cubic 
inches) could be drawn from it by observing the time which the water of the trough 
took to rise from the mark b to c. The perforated brass plate, through which the gas 
had to pass, was attached to the stopcock L, as before, and was therefore within the 
tube H. It is represented of one-fourth of its linear dimensions in fig. 5, Plate 
XXXIII. 
4 g 2 
