76 
MISCELLANY. 
means of the chlorate of potash. One atom of KCr 2 produces three 
atoms of free oxygen, and leaves a residue composed of KS + Cr Ss» 
with which a new quantity of bichromate may be readily prepared. — 
Ibid. 
Bichloride of Hydrogen, — M. Millon states to have found a combina- 
tion of hydrogen and of chlorine which contains double the quantity of 
chlorine that exists in hydrochloric acid. If, to hydrochloric acid, arti- 
ficially cooled by means of a mixture of ice and salt, we add a small 
quantity of peroxide of lead, a precipitate of chloride of Lead is thrown 
down, without any disengagement of chlorine ; but we obtain a deep 
yellow liquid, which disengages chlorine during several days on expo- 
sure to the ordinary temperature of the air. To prove that this combi- 
nation is formed of H CI 2, he quotes that mercury, by its reaction upon 
it, produces chloride of mercury and hydrochloric acid. Zinc, added in 
small pieces, dissolves also without any disengagement of gas. These 
proofs are not very conclusive, for the same thing would take place with 
cold liquid hydrochloric acid in which chlorine gas had been condensed. 
But, on the other hand, as there exist corresponding combinations with 
brome and iodine, it is very probable that there also exists one with 
chlorine, and that it may be produced in this manner. The most easy 
way of preparing it would be to pass a stream of chlorine through very 
cold concentrated hydrochloric acid, or else to add liquid chlorine till 
saturation; or, again, one might endeavour to reduce, below the tempe- 
rature of deg. cent., a mixture of two volumes of hydrochloric acid and 
one volume of chlorine, and see if any condensation takes place, — Ibid. 
Cement for Stone Ware, Earthen Ware, §rc. — Is best obtained by melt- 
ing together 3 parts sulphur, 2 parts white resin, 1 half part shell-lac, 
1 part elemi, and I part mastic, with 3 parts brickdu?t. This cement is 
spread on the previously warmed surfaces. — Chem. Gaz. 
On the Composition of the Profocarbonate of Iron. By M. Wittstein. — 
The carbonate of the protoxide of iron, precipitated by powdered crys- 
talized carbonate of soda from a boiling solution of recently-prepared 
protosulphate of iron, washed by decantation, well-pressed in linen and 
dried, contains, according to Wittstein, protoxide of iron, water and car- 
bonic acid, in the proportion of 46.7: 13.6 : 28.7, which corresponds to 
the formula FeO CO2, HO. Moreover, a variable quantity of hydra ted 
peroxide of iron is always mixed with it. The salt becomes heated in 
the air, disengages carbonic acid, and passes into hydrated peroxide, 
losing nearly 23 per cent, in weight. The residuous reddish-brown 
