42 Improvements tr Physical Science [Jaw. 
black oxide of manganese were mixed in a common phial with six 
parts of strong sulphuric acid. ‘The phial was put into a crucible 
surrounded with sand, and exposed for an hour and a half to a dull 
red heat. The white mass thus formed was thrown into cold water, 
and, after being digested a sufficient time, the liquid was filtered. 
A colourless solution is thus obtained, which, being set aside in a 
warm place, yields regular crystals of pure sulphate of manganese. 
(Schweigger’s Journal, xiv. 336.) 
2. Metaliine Muriates.—It is at present nearly the general 
opinion of chemists that when the chlorides of the different metals 
are dissolved in water, they are converted into muriates. M. 
Chevreul has pointed out some facts which strengthen that opinion. 
Though these facts are not new, yet 1 shall state them here, because 
they are likely to appear more striking when collected together than 
when considered in an insulated state. (1.) Proto-chloride of iron 
is white; but becomes green when dissolved in water, and crystal- 
lizes in polyhedrons of the same colour. (2.) Perchloride of iron 
forms an orange-brown solution, which crystallizes in yellow 
needles. (3.) Chloride of cobalt is grey; but when thrown into 
water, it forms a red solution, like the proto-sulphate, proto-nitrate, 
and prot-acetate of cobalt. (4.) Chloride of nickel is golden-yellow, 
but it forms a green solution in water, like the proto-sulphate, 
proto-nitrate, and prot-acetate of nickel. (5.) Perchloride of 
copper is yellow; but its concentrated solution is green, and it be- 
comes blue when diluted, like the other solutions of peroxide of 
copper. (Ann. de Chim. xev. 308.) 
3. Chloride of Aluminu.—Ove of the most beautiful parts of 
calico printing is the art of discharging the Turkey red dye from 
different parts of a piece of cloth, which may be either left white or 
printed afterwards at pleasure. This process is performed by means of 
chlorine. Chloride of lime is dissolved in water, and decomposed 
by means of sulphuric or muriatic acid. The liquid thus im- 
pregnated with chlorine is applied in a very ingenious way, of which 
a description has been given by Mr. Wilson in the Annals, viii. 125. I 
have been informed that this ingenious process originated in Glasgow; 
and I will take it as a favour if any of my readers will furnish me with 
a history of the discovery. Mr. Wilson has found that chloride of 
alumina answers the purpose of discharging the Turkey red dye fully 
as well as pure chlorine, whiie it has the advantage over it of not 
injuring the texture of the cloth, and of not annoying the vorkmen 
by its noxious smell. He prepares it by adding to a solution of 
chloride of lime, of the specific gravity 1°060, a solution of alum 
of the specific gravity 1:100, as long as any precipitate falls. The 
precipitate is to be separated, and the clear liquid kept for use in 
close vessels. (See Annals, viii, 127.) : 
4. Chlorates.—W hen my historical sketch of the progress of the 
sciences during 1815 appeared in the Annals for last January, M. 
Vauquelin’s paper on the chlorates had not been all published ; or 
at least the number of the Ann. de Chim. for August, 1815, had 
