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PROFESSOR GRAHAM ON THE CONSTITUTION OF 
2 . Chloride of Manganese. 
MnCl H 2 + 2 H. 
Experiment. — Of the flesh-coloured crystals, 15*53 grains, precipitated by nitrate 
of silver, gave 22*57 grains of chloride of silver, equivalent to 5*56 chlorine, or to 
9*92 chloride of manganese, which leaves 5*61 grains water in the salt, or 36’] 2 per 
cent, of water. Now a chloride of manganese with four atoms of water would con- 
tain 36*33 per cent, of water. 
This salt readily lost half its water when dried at 212° in open air, or when dried 
over sulphuric acid in the vacuum of an air-pump at the ordinary temperature. But 
when the exposure of the salt in such circumstances was long protracted, a little of 
the constitutional water also was lost. 
3. Protochloride of Iron. 
Fe Cl H 2 + 2 H. 
In three experiments made upon different specimens of crystallized protochloride 
of iron, all newly and very carefully prepared, 13*69 grains chloride of silver were 
precipitated from 9*72 salt, 17*20 chloride of silver from 12*44 salt, and 15*75 chlo- 
ride of silver from 11*21 salt. These experiments almost coincide in their results, 
which are, that 1 part of the salt contains 0*3466, 0*3463, and 0*3461 of chlorine. 
But such proportions of chlorine are decidedly under the proportion which a neutral 
salt with four atoms of water should contain, namely, 0*3593 chlorine. Indeed, the 
quantity of water in the salt is indicated by these experiments to be four and a half 
atomic proportions almost exactly. By crystallizing from an acid solution Bonsdorff 
has lately obtained this salt in a state of purity, and containing four atoms of water. 
4. Chloride of Magnesium. 
MgCl H 2 + 4 H. 
Of the crystals of this salt, which are decidedly deliquescent, 12*65 grains were 
found to contain 4*29 chlorine ; or the salt contains 33*91 per cent, of chlorine, which 
approaches sufficiently near to the theoretical proportion 34*69 per cent., supposing 
the salt to contain six atoms of water. 
5. Chloride of Calcium. 
CaCl I 1 ! 2 + 4 H. 
The crystals of this deliquescent salt, dried in vacuo till they began to effloresce, 
were found to contain six atoms of water, the proportion usually allotted to them ; 
but it is remarkable, that, continued in vacuo over sulphuric acid for ten days during 
