REPORT ON CHEMISTRY*. 
449 
ceiver without the bladder, is equal. But this diffusion pro¬ 
ceeds in such a way, that for every volume of common air which 
passes out of the bladder, 3*79 volumes of hydrogen pass into 
it; and hence its remarkable expansion. Now 3*79=— t== a > 
V0*694 
where 0*694 represents the density of hydrogen gas. 
Again, if hydrogen he introduced into the bladder, and it be 
left in the open air, the tendency is the same; but as there is 
no proportion between the volume of hydrogen in the bladder 
and that of air in the atmosphere, the latter replaces the former 
entirely ; but for every 3*79 volumes of hydrogen at the com¬ 
mencement, only one of air will be found in the bladder at the 
conclusion of the experiment. 
The instrument employed by Mr. Graham in his experiments 
■—his diffusion tube —is a graduated tube, half an inch in dia¬ 
meter and twelve or fourteen in length, with or without a bulb 
blown into it towards the upper end, which is closed with a plug 
of plaster of Paris dried at 200° Fahr. A plug of this descrip¬ 
tion he found to absorb 6*5 times its volume of ammoniacal gas, 
0*75 of sulphurous acid gas, 0*5 of cyanogen, 0*45 of sulphu¬ 
retted hydrogen, and 0*25 of carbonic acid; and for these quan¬ 
tities allowance was made in deducing the results of experi¬ 
ment. The other gases tried were not absorbed in any sensible 
quantity. 
The diffusion tube was filled with the gas, whose volume of 
diffusion was to be ascertained, and inverted over water in the 
open air. The diffusion took place through the plug, and one 
volume of air replaced the other gases in the proportions noted 
in the following Table. 
By Experi¬ 
ment. 
By Theory, 
1 
or — 
D§* 
Spec. Gray. 
Hydrogen.. 
3*83 
3*7947 
0-694 
Carburetted hydrogen 
1-344 
1-3414 
0*555 
Olefiant gas . 
1-0191 
1-0140 
0-972 
Carbonic oxide. 
1-0151 
1-0140 
0-972 
Nitrogen . 
1-0145 
1-0140 
0-972 
Oxygen .. 
0-9487 
0-9487 
1-111 
Sulphuretted hydrogen 
0-95 
0-9204 
1*1805 
Protoxide of azote. . . . 
0-S2 
0-8091 
1*527 
Carbonic acid .. 
0-812 
0-8091 
1*527 
Sulphurous acid . 
0-68 
0-6708 
2*222 
The numbers in the second and third columns of this Table 
2 F 
