MISCELLANY. 
237 
precaution, this process may be made to yield £| ths, or nearly the 
whole theoretical amount of the gas. — Silliman's Journal. 
On the Preparation of crystallized Sulphuret of Calcium. By Dr. E. 
RiEGEL.~The best process for procuring pure sulphuret of calcium is 
that recommended by Liebig, according to which 4 parts calcined gyp- 
sum, 1 part powdered charcoal, and \k part meal, are kneaded with 
water to a paste, which is formed into pellets, which when perfectly 
dry are arranged with charcoal in alternating layers, and exposed to a 
red heat. On heating to redness a mixture of equal parts of hydrate of 
lime and sulphur, a preparation is obtained which contains a considera- 
ble quantity of sulphate of lime. On boiling 1 part hydrate of lime 
with 2^ parts sulphur and 16 parts water for a length of time, the 
author obtained a brownish-yellow solution, from which on cooling 
some red acicular prisms separated. The crystals were quickly de- 
composed by exposure to moist air. — Chem. Gaz. from Jahrb. f ur Prakf. 
Chern. 
Stopping for the Teeth. By M. Bernoth, of Warasdin. 
U Powdered mastic 90 grammes. 
Sulphuric ether 40 " 
Digest for several days, strain it through a cloth, then add native alum 
in fine powder, in sufficient quantity to form a plastic mass, with which 
small phials, holding 8 grammes, are to be filled, having first poured 
into each 
Camphorated alcohol 2 grammes. 
Essence of cloves 1 gramme. 
This stopping introduced into the cavity of a carious tooth, first well 
cleaned and dried, is extremely useful on account of the great degree 
of hardness it acquires. — Chemist, from Archiv. dc Phar. 
Advantageous Method of preparing Gallic Acid. By F. Mueller. — 
The author recommends Braconnot's method for preparing gallic acid, 
modified as follows. He boils 16 oz. of coarsely-pounded so-called 
heavy blue galls three times with 8 lbs. of water in a tin sauce-pan, 
strains the decoction, and lets it stand for 4 months in a covered 
earthenware pan, at a temperature of 100° — 122°, now and then re- 
placing the evaporated water and well agitating. The mould, as well 
as the crusts which form, are after this time collected on a filter, 
slightly washed with cold water and dried, then boiled with 4 parts 
waier, filtered, and the residue well washed with hot water. The 
crystals which separate from the filtered solution on cooling are sepa- 
