PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
809 
The diffusion-time of bromine was made ten days, or double the time of hydro- 
bromic acid. Two cells contained together a diffusate of 5’80grs. of bromine; an- 
other two cells a diffusate of 5'88grs. ; mean 5‘84grs. at 60°T Fahr. ; or 6'76 grs. for 
a 1 per cent, solution. Doubling the last result we have 13'52grs. for a 2 per cent, 
solution, which is still considerably under the diffusate of hydrobromic acid (1 6‘58 grs.) 
in half the time. 
3. Hydrocyanic Acid. 
Time of diffusion five days. The acid diffused was estimated from the cyanide of 
silver which it gave with nitrate of silver. 
Hydrocyanic acid, T766 per cent., made up to a density of 1*0142 with sulphate of 
potash. Diffused at 64°*2, in six cells, 11*40, 11*86, 11*80; mean 11*68 grs. for two 
cells. Calculated for 2 per cent., 13*23 grs. at 64°*2 in two cells, or about 13*10 grs. 
at 62°*8, assuming this acid to be affected in the same way by temperature as hydro- 
chloric acid. 
Hydrocyanic acid here appears less diffusive than hydrochloric acid, at the same 
temperature 62°*8, as 13*10 to 16*40, or as 79*6 to 100, and not to belong therefore 
to the same class of diffusive substances. 
4. Nitric Acid. 
Time of diffusion five days. The quantity of this acid diffused was always deter- 
mined with great exactness by neutralization by means of a normal solution of car- 
bonate of soda. 
1. Nitrate of water (HO.NO5), 1 per cent.; density 1*0052. Diffused at 50°*8, in 
eight cells, 6*77? 6*77, 7*26, 6*97 ; mean 6*94 grs. of nitrate of water in two cells at 
50°*8, and 6*99 grs. by estimate at 51°*2. 
2. Nitrate of water, 1 per cent.; density 1*0052. Diffused at 53°*5, in six cells, 
7*32, 7*32, 7*20 ; mean 7*28 grs. in two cells. 
3. Nitrate of water, 1*92 per cent.; density 1*0112. Diffused at 51°*2, in eight 
cells, 14*34, 14*24, 14*10, 13*96; mean 14*16 grs. in two cells. Calculated for 2 per 
cent., 14*74 grs. at 51°*2 in two cells. 
4. Nitrate of water, 2 per cent.; density 1*0106. Diffused at 63°*2, in eight cells, 
16*97, 16*64, 16*81, 16*64 ; mean 16*76 grs. in two cells. 
5. Nitrate of water, 3*88 per cent. ; density 1*0209. Diffused at 51°*2, in eight cells, 
27*76, 28*34, 27*90, 27*62 ; mean 27*90 grs. in two cells. Calculated for 4 per cent., 
28*76 grs. at 51°*2 in two cells. 
6. Nitrate of water, 7*96 per cent. ; density 1*0432. Diffused at 51°*2, in four cells, 
29*17, 29*17, 29*17, 27*76 ; mean 28*82 grs. in one cell. Calculated for 8 per cent., 
28*96 grs. at 51°‘2 in one cell. 
For the difference of temperature between 51°*2 and63°*2, the diffusion rises, in the 
2 per cent, solution, from 14*74 to 16*76 grs., or from 100 to 113*7 ; which gives an 
increase of 1*142 per cent, for one degree of temperature. 
5 L 
MDCCCL. 
