80 Intelligence and Miscellaneous Articles. 
rotatory power, comparable to that of the salts of cobalt; the salts 
of the sesquioxide possess too much colouring power to be adapted 
for these experiments. Nothing, however, is easier than to prove 
the magnetism of the three preceding metals and their salts. 
Chromium.—The protosalts of chromium are difficult to prepare ; 
those of the sesquioxide have so much colouring power that they 
cannot be dissolved in verysmall quantity in water without destroying 
all its transparency; but chromic acid and some chromates are very 
convenient for experiments. Neutral chromate of potash has a 
weak negative rotatory power, which, however, it is impossible to 
mistake ; the rotatory power of the bichromate is also negative, and 
greater than that of the neutral salt; chromic acid has a negative 
rotatory power comparable to that of the protosalts of iron. Chromic 
acid and bichromate of potash are magnetic, whilst the neutral 
chromate is diamagnetic. On comparing this circumstance with 
the observations relative to the ferrocyanide of potassium, we shall 
be led to conclude that the positive rotatory power of the latter is 
not due to its being diamagnetic, but to the physical properties of 
the iron being as completely masked as its chemical properties in 
this compound*. 
Titanium.—Bichloride of titanium, which is liquid at ordinary 
temperatures, has a negative magnetic rotatory power, a little superior 
in absolute value to the magnetic rotatory power of water. The 
author could not ascertain with certainty whether it is magnetic or 
diamagnetic; pure titanium is magnetic. Titanium is generally 
regarded as allied to tin, and the bichloride in particular as analogous 
to bichloride of tin. It is remarkable, that, under the influence of 
magnetism these two bodies exert contrary actions upon polarized 
light. 
" Oariimi GA. concentrated solution of sulphate of cerium and a so- 
lution of chloride of cerium, appeared to possess a magnetic rotatory 
power a little less than that of water. It is therefore probable that 
the rotatory power of the salts of cerium is negative. The mag- 
netism of these salts is as evident as that of the salts of chromium or 
manganese. 
Thus, by the properties which they communicate to their trans- 
parent compounds, the magnetic metals are divided into two series, 
—one containing iron, chromium, titanium, and probably cerium, 
the other including nickel, cobalt and manganese. It is worthy of 
remark, that the most strongly magnetic metals, iron and nickel, are 
the types of these two series, and that the less magnetic metals, as 
it were, establish the transitions.—Comptes Rendus, June 8, 1857, 
p. 1209. 
* In studying the optical properties of the strongly-coloured solutions 
furnished by the persalts of iron, the salts of nickel, cobalt and chromium, 
and the chromates, it is essential to take into account the influence of the 
coloration upon the position of the tint of passage. Serious errors will 
be committed if the necessary correction be neglected. 
