PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
829 
Diffusion of Chloride of Potassium, 1 per cent, solution; two cells. 
Time. 
Temperature. 
Diffusion in two cells. 
Differences, 
5 days. 
55°71 
5*89 
5 days 10 hours. 
55*90 
6*25 
0*36 
5 days 20 hours. 
55*79 
6*55 
0*30 
6 days 6 hours. 
55*79 
6*71 
0T6 
6 days 16 hours. 
55*90 
6*95 
0*24 
7 days 2 hours. 
55*9 
7*48 
0*53 
7 days 12 hours. 
55*9 
7*58 
0*10 
7 days 22 hours. 
56*03 
8*08 
0*50 
8 days 8 hours. 
56*28 
8*34 
0*26 
8 days 18 hours. 
56*15 
8*60 
0*26 
When the quantities of chloride of potassium are placed beside the same quantities 
of hydrochloric acid in the former Table, it is found that the times of diffusion of 
the salt and acid exhibit an approximately constant ratio. The squares of these times 
of equal diffusion are as 1 to 2’04 for the shortest period of the chloride of potassium, 
and as 1 to 2T0 for the longest period but one. The variation in the differences 
towards the middle of the Table is too great to be explained, except I fear by some 
error of observation, although no ordinary precaution was neglected in the execution 
of this laborious series of experiments. 
34. Iodides and Bromides of Potassium and Sodium. 
Iodide of Potassium. — Time of diffusion 5’716 days. The diffusate was estimated 
by means of nitrate of silver. 
(1.) Iodide of potassium, 1*977 per cent.; density T0145. Diffused at .53°*5, in 
eight cells, 1T415, 11*.506, 10*942 and 11*062 grs. ; mean 11*24 for two cells, and 
11*36 for two per cent. 
Comparing this salt with the isomorphous chloride of potassium, we have — 
Diffusion of 2 per cent, solutions in 5*716 days. 
Chloride of potassium at 55° . . . 11*48 100 
Iodide of potassium at 53°*5 . . . 11*36 99*65 
The diffusion of the iodide would slightly exceed that of the chloride, instead of 
falling below it as in the Table, if the temperatures were made equal. 
(2.) Again, iodide of potassium 1*971 percent., observed density 1*01486. Diffused 
at 59°*8, in eight cells, and the mean diffusate of the whole cells determined, it gave 
12*33 grs. of iodide of potassium for two cells ; or 12*51 grs. for a 2 per cent, solution. 
Bromide of Potassium. — Time of diffusion and mode of estimating diffusate as above. 
The solution contained 1*975 per cent, of salt, and had a density of 1*014850. Diffused 
