544 MR. J. S. TOWNSEND ON MAGNETIZATION OF LIQUIDS. 
to the weights of iron per cub. centim. This shows that the action of the solvent is 
to diminish the value of 10 7 & by 77, which is the value of — ] 0 7 & for water. 
The actual values found for distilled water in three different experiments were 
I0 7 k = - 8’1, - 7-5, and - 7‘5, 
the mean being — 7'7. 
The values for 10 7 k for water given by different observers are:— 
Henrichsen — 7 - 51, Quincke —4-278, Howard —4-248, and Wabner —2758.* 
A solution of ferric chloride, whose value for 10 7 & at 10° centigrade, was 
230-5 - 7-7, 
was found by gravimetric analysis to contain *0865 gram of iron per cub. centim. 
Hence the general formula for h, for ferric chloride dissolved in water, is 
10 7 A- = 2660 W — 7'7 
W being the weight of iron per cub. centim. of the solution. 
Ferric Sulphate. 
The values of Jc for three different solutions of ferric sulphate were found, the 
quantity of iron per cub. centim. in each being proportional to 2, 3, and 4, giving the 
values 
52, 79-3, and 110, for 10 7 ^. 
If to these we add 7*7 we get the values of Jc for the salt alone which are in the 
same proportion as the quantity of salt per cub. centim. 
A solution, whose value for 10 7 & at 7° centigrade was 86‘2 — 77, contained -0320 
gram of iron per cub. centim., which gives for ferric sulphate the formula 
10 7 & = 2690 W — 7-7. 
It will be seen from the curves showing the variation of Jc with temperature that 
at 10° centigrade the value of h will be 1*5 per cent, less than at 7°, so that we get 
10 7 A: = 2660 W — 7*7, at 10° centigrade, 
exactly the same formula as for ferric chloride. 
* Wiedemann, 1 Electricitat,’ vol. 3, pp. 1292 and 1322. 
