PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
I 
Diffusion of Chloride of Sodium. 
Proportion of salt to 100 water. 
Diffusion product. 
In grains. 
Ratio. 
1 
At 39°*6 
2-63 
1- 
2 
At 39°*6 
5-27 
2-00 
3 
At 39°-6 
7*69 
2-92 
4 
At 39-°6 
10- 00 
3-80 
1 
At 67° 
3-50 
1- 
2 
At 67° 
6-89 
1*97 
3 
At 67° 
9*90 
2-83 
4 
At 67° 
13-60 
3-89 
The proportionality in the diffusion is still well-preserved at the different tempe- 
ratures. The deviations are indeed little, if at all, greater than might be occasioned 
by errors of observation. The ratio of diffusion, for instance, from the solutions 
containing 4 parts of salt, is 3'80 and 3‘89 for the two temperatures, which numbers 
fall little short of 4. 
The diffusion manifestly increases with the temperature, and as far as can be 
determined by three observations, in direct proportion to the temperature. The dif- 
fusion-product from the 4 per cent, solution increases from lOgrs. to 13‘60, with a 
rise of temperature of 27°'4, or rather more than one-third. Supposing the same 
progression continued, the diffusibility of chloride of sodium would be doubled by a 
rise of 84 or 85 degrees. 
(3.) The progress of the diffusion of chloride of sodium in such experiments as 
have been narrated, was further studied by intercepting the operation after it had 
proceeded for different periods of 2, 4, 6 and 8 days. The solution employed was 
that containing 4 parts of salt to 100 water. Two of the six-ounce phials were di^ 
fused at the same time for each period. The temperature given is the mean of the 
temperatures of a water-jar observed each day of the period. The daily fluctuation 
was not more than two or three-tenths of a degree Fahr. 
In 2 days, temperature 63°'7 ; the salt diffused was 4‘04 and 3‘86 grs. ; mean 
3‘95 grs. 
In 4 days, temperature 63°‘7 ; the salt diffused was 678 and 7’ 12 grs.; mean 
6*95 grs. 
In 6 days, temperature 63°'8 ; the salt diffused was 10’02 and 9‘7fl gi’s. ; mean 
9'86 grs. 
In 8 days, temperature 64®; the salt diffused was 13*00 and 13*25 grs.; mean 
13*12 grs. 
The proportion diffused in the first period of two days is given directly in the first 
experiments. The proper diffusion for each of the three latter periods of two days is 
obtained by deducting from the result of each period the result of the period which 
precedes it : — 
