MISCELLANY. 
319 
described in the preceding paper, there is obtained, instead of a dia- 
phanous product, an opake substance, which becomes entirely transpa- 
rent when placed in water, in a word, true hydrophane. It suffices 
for this purpose that the silicic aether employed retain a little chloride 
of silicium, which happens when an excess of alcohol has not been 
employed in the preparation of the aether. On exposing this aether, 
still somewhat acid, to the action of moist air, there is obtained a solid 
mass, which is at first transparent, but ends by becoming opake after 
some week's exposure to the air. The translucidity of this substance 
is so much the less the greater the proportion of the chloride of silicium 
in the aether. Some of the fragments have the semi-transparency of 
opal. They all become entirely transparent in water. 
We are therefore able artificially to reproduce hydrophane, this rare 
variety of quartz, and the curious properly of which had struck mine- 
ralogists. 
A very small proportion of foreign substances suffices in fact to 
modify the translucidity and the appearance of the hydrate of silica ; 
thus a small flask containing silicic aether having been closed by mis- 
take with a cork, which belonged to a bottle full of creosote, the aether, 
on becoming coagulated under the action of moist air, yielded a slight- 
ly yellowish silica, and merely translucid like chalcedony • the product 
thus obtained was not hydrophanous. 
I propose to continue and to vary these experiments, which appear 
to me of great importance and of considerable interest. — Ibid, from 
Comp. Rendus. 
Indelible Ink — May be prepared by adding lamp-black and indigo to 
a solution of the gluten of wheat in acetic acid. This ink is of a beauti- 
ful black colour, at the same time cheap, and cannot be removed by 
water, chlorine, or dilute acids. M. Herberger gives the following di- 
rections for its preparation: — Wheat-gluten is carefully freed from the 
starch, and then dissolved in a little weak acetic acid ; the liquid is 
now mixed with so much rain-water that the solution has about the 
strength of wine-vinegar, i. e. neutralizes one-sixteenth of its weight of 
carbonate of soda. 10 grs. of the best lamp-black and 2 grs. of indigo 
are mixed with 4 oz. of the solution of gluten and a little oil of cloves 
added. This ink cannot be employed for marking linen, as it does 
not resist mechanical force. — Ibid, from Jahrb. fur Prakt. Pharm. 
Detection of Impurities in Disulphate of Quinine. — The following test for 
the adulteration of disulphate of quinine is recommended by Dr. Nevius 
of Liverpool, on account of its delicacy and simplicity : — To 1 or 2 grs. 
of the suspected salt add 3 or 4 drops of sulphuric acid in a white 
