546 
MR. J. S. TOWNSEND ON MAGNETIZATION OF LIQUIDS. 
Weight of iron in ferrous state, per cub. centim., '0689, 
Weight of iron in ferric state, per cub. centim., •0064, 
10 7 £ = 158 - 77, 
subtracting 17, which is the value of 10 7 k for ‘0064 gram per cub. centim. in ferric 
sulphate, we get 
10 7 k = 141 — 7*7 for '0689 of iron in the ferrous state. 
Hence 
10 7 k = 2050 W — 77, 
differing from the formula obtained for ferrous chloride by only *5 per cent. 
The same result was obtained for a solution containing ’01 gram of ferric iron and 
'0118 of ferrous iron. 
The presence of free sulphuric acid in the sulphates was found not to affect the 
value of k, by testing whether an addition of the acid altered it. 
The liquid containing the two sulphates in nearly equal proportions was further 
examined by gradually neutralizing the free sulphuric acid with caustic potash till 
an almost neutral solution was obtained. 
This did not alter the coefficient of magnetization of the salt, showing that no 
change in the acid radical had as yet taken place, but when the potash was added 
till the dark precipitate was formed, the value of k immediately rose. 
This experiment shows that a salt corresponding to the magnetic oxide does not 
exist in solution, and that when the latter is dissolved in an acid it gives a mixture 
of ferrous and ferric salts. 
Salts in the Dry State. 
Estimations were also made in the dry state by filling a glass tube with the salt 
and putting it into the solenoid. These experiments could not with ease be per¬ 
formed with the same accuracy as those made on the solutions, since the density of 
the salt is variable along the tube, and the amount of moisture and water of crystal 
lization in the body introduce errors when estimating the weight of iron. 
The experiments showed roughly that the magnetic properties of the salts are the 
same as when they are in solution, the actual numbers got for ferrous sulphate were 
10 7 /’ =841, the amount of iron per cub. centim., found by weighing the body as 
EeSoj, I- 7H 2 0, was ’241. This value of k differs by only 4 per cent, from the value 
calculated from the formula 10 7 /r = 2050 W. 
Don in the Acid Radical. 
Solutions of potassium ferricyanide and ferrocyanide each containing '029 gram of 
