PROFESSOR GRAHAM ON THE DIFFUSION OF LIQUIDS. 
11 
Table IV. — DifFiision of solutions of 10 salt to 100 water at 37°‘5. 
Name of salt. 
Anhydrous salt diffused. 
In grains. 
Means. 
Chloride of sodium 
22-21 
Chloride of sodium 
22-74 
22*47 
Nitrate of soda 
22-53 
Nitrate of soda 
23-05 
22-79 
Chloride of ammonium 
31-14 
31-14 
Nitrate of potash 
28-84 
Nitrate of potash 
28-56 
28-70 
Nitrate of ammonia 
29-19 
29-19 
Iodide of potassium 
28-10 
28-10 
Chloride of barium 
21-42 
21-42 
Sulphate of water 
31-11 
Sulphate of water 
28-60 
29-85 
Sulphate of magnesia 
13-03 
Sulpliate of magnesia 
13-11 
13-07 
Sulphate of zinc 
11-87 
Sulphate of zinc 
13-33 
12-60 
The near equality of the quantities diffused of certain isomorphous salts is striking' 
at both temperatures. Chloride of potassium and chloride of ammonium give 40’ 15 
and 40'20 grs. respectively in the first table. Nitrate of potash and nitrate of 
ammonia 35’55 (mean) and 35’3 grs. respectively in the first table, and 28*70 and 
29*19 grs. in the second table. Sulphate of magnesia and sulphate of zinc 15*45 
and 15*8 grs. (means) in the first table, with 13*07 and 12*60 grs. in the second. 
The relation observed is the more remarkable, that it is that of equal weights of the 
salts diffused, and not of atomically equivalent weights. In the salts of ammonia 
and potash, this equality of diffusion is exhibited also, notwithstanding considerable 
differences in density between their solutions ; the density of the solution of chloride 
of ammonium, for instance, being 1*0280 and that of chloride of potassium 1*0596. 
It may have some relation however, but not a simple one, to the density of the solu- 
tions ; sulphate of magnesia, of which the solution is most dense, being most slowly 
diffusive ; and salts of soda being slower, as they are generally denser in solution, than 
the corresponding salts of potash. Nor does it depend upon equal solubility, for in 
none of the pairs is there any approach to equality in that respect. 
A comparison was now made of the diffusibility of several acids. They were dif- 
fused from the same six-ounce phials, and for eight days. Solutions were prepared in 
the proportion of 4 parts of the anhydrous acid to 100 parts of water. The quantity 
of acid which diffused into the water-jar was estimated by the proportion of carbo- 
nate of soda which it neutralized. 
