PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
33 
chromate of potash, in the proportion of 100 to 105’2, is certainly remarkable, unless 
due to a slight decomposition of the latter. 
(7.) Ferrocyanide and Ferricyanide of Potassium. 
Of these two salts the 1 per cent, solution only was diffused. The time of diffusion 
was seven days, as usual ; the mean temperature 54°‘5. In evaporating the liquid of 
the water-jars, both salts were partially decomposed, so that it became necessary to 
estimate the diffusion product by a determination of the potash. Eight cells were 
employed for one salt and six for the other, and the liquids of the water-jars evapo- 
rated two together. 
The diffusion product of ferrocyanide of potassium (anhydrous) was 5*02, 5*22, 
5*02 and 5*20 grs. ; mean 5T2 grs., or for one cell 2'56 grs. 
The diffusion product of ferricyanide of potassium was 5*54, 5'64 and 5*36 grs. ; 
mean 5*51 grs., or for one cell 2*75 grs. 
Three cells of a similar solution of sulphate of potash which were diffused for seven 
days at a mean temperature 1° lower, or of 53°*5, gave 2*56, 2*53 and 2*62 grs. ; 
mean for one cell 2*57 grs., a number which almost coincides with that of the ferro- 
cyanide of potassium (2*56 grs.). The ferricyanide of potassium, on the other hand, 
is sensibly more diffusive, as 107‘6 to 100, and appears to rank with the bicarbonate 
and bichromate of potash. The ferricyanide of potassium, again, is a salt which 
probably undergoes a slight decomposition in diffusion like those salts mentioned : — 
Diffusion of 1 per cent, solutions. 
Sulphate of potash 2*57 grs. at 53°*5. 
Ferrocyanide of potassium . . 2*56 grs. at 54°*5. 
Ferricyanide of potassium . . 2*75 grs. at 54°*5. 
The salts of the nitre class may also be compared in the same manner, and I shall 
now add a third series of results obtained from the diffusion of 1 per cent, solutions 
of the same salts. The temperature of diffusion of this new series was 64°*5. Six 
phials of each salt were diffused, and they were evaporated afterwards two and two. 
This double diffusion product, however, is divided by 2 in the table. 
Diffusion of Salts of the Nitre Class. 
4. 
2 . 
1 . 
Nitrate of potash 
13-97 
7*47 
3-72 
Nitrate of aiumonia 
14-48 
7-73 
3-75 
Chloride of potassium 
15-01 
7*70 
3-88 
Chloride of ammonium 
14-41 
7-81 
3-89 
Chlorate of potash 
13-31 
7-22 
3-66 
Mean 
14-23 
7-58 
3-78 
MDCCCL. 
F 
