PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
821 
tions, either in six or in eight cells. The salt diffused was estimated by means of 
nitrate of silver. 
22. Chloride of Zinc at 51°, solution of density T0091, gave6‘55, 6‘20, 6'21 and 6‘28 
grs. ; mean 6‘29 for two cells. 
23. Chloride of Magnesium at 50°‘6, density T0077j gave 6-40, 5‘84 and G‘29 ; mean 
6T7 for two cells. 
24. Chloride of Copper at 50°'6, solution of density r0093, gave 6’08, 6'08 and 
6‘02 grs. ; mean 6’06 for two cells. 
The results referied to chloride of calcium, at nearly the same temperature, 50°-8, 
are as follows : — 
Chloride of calcium . . 
. 6*51 
100 
Chloride of zinc . 
. 6*29 
96-61 
Chloride of magnesium . 
. 
. 6*17 
94-77 
Chloride of copper 
. 
6*06 
93*08 
These salts present a greater latitude in their diffusibility, if belonging to the same 
class, than is usual. 
25. Protochloride of Iron. 
A solution of this salt of T023 per cent, was diffused at 53°*5, a somewhat higher 
temperature than the corresponding chlorides. It gave 6‘45, 6'48, 6’48 and 6‘28 grs. 
in two cells ; mean 6’44, or 6‘30 for 1 per cent, in two cells. This salt appears there- 
fore to belong to the last group. 
26. Sesquichloride of Iron. 
A full series of observations was made upon the diffusion of the different propor- 
tions of this salt from 1 to 8 per cent., but in all of them decomposition was deter- 
mined by the diffusion, with turbidity also in the solution phial except in the 8 per- 
cent. solution. 
The mean diffusion from the 1 per cent, solution in 1T43 days, at 63°*3, was 4-13 
grs. of sesquichloride of iron with T28 gr. of free hydrochloric acid, in two cells. This 
result indicates that one-half nearly of the sesquichloride of iron is decomposed in 
the diffusion. 
The mean diffusion from the 8 per cent, solution, at 63°-3, was 55*88 gi-s. of sesqui- 
chloride of iron, with 6*66 grs. of free hydrochloi-ic acid, in two cells. It appears 
from this expei-iment that perchloride of ii*on approaches the chloride of calcium in 
diffusibility. That the proto- and persalts of the magnesian metals should have a 
similar rate of diffusion, is not unlikely from other analogies which they exhibit. 
27 . Sulphate of Magnesia. 
The time chosen for the diffusion of this salt, namely, 16*166 days, is a multiple 
by 2 of the time of sulphate of potash, and by 4 of the time of hydrate of potash. 
The diffusate was evaporated to dryness and weighed. 
