80 
MISCELLANY. 
of considerable loss to me, the purchaser refusing the cantharides, be- 
cause not genuine and of inferior quality. In fact, the Lytta Syriaca is 
one-third smaller than the Lytta Vesicatoria, and its red tarsus is less 
vesicating, as has been proved by experiment. Although this admix- 
ture has been rarely observed since in commerce, it has appeared to me 
that it would be proper to point it out — Journ. de Pharm. 
Aqueous infusion of Galls as a test. — This is best prepared according 
to M. Pettenkofer by infusing one part of pounded galls in three or four 
parts of water, allowing it to stand for several hours, straining, submit- 
ting the residue to pressure, adding to the turbid liquid two parts of 
common salt, and separating by filtration the glutinous precipitate which 
is produced. This liquid retains its transparency and power of preci- 
pitating gelatin for years — Buchn. Repert. and Chem. Gaz. 
Preparation of Mercurial Ointment. — M. Heusler recommends the fol- 
lowing method : — 6 oz. of Mercury, 2 oz. of Suet, and 6 oz. of Lard, 
are rubbed together in a shallow 7 iron mortar with the addition of about 
a drachm of sulphuric ether at intervals, until all the globules have dis- 
appeared. 
The process occupies about three quarters of an hour, and the quan- 
tity of ether required is about 7 drachms. — Jahrb.fur Prakt. Pharm. and 
Chem. Gaz. 
Aqua Sinapis. — According to M. Heusler by the distillation of 18 oz. 
of coarsely powdered black mustard, with 8 oz. of alcohol and sufficient 
water, until 36 ounces have passed over, a liquid is obtained, which, 
when applied to the skin or linen moistened with it, acts more quickly 
and powerfully than an ordinary mustard-poultice. — Ibid. 
Preparation of pure Nitrogen. — Pure nitrogen is obtained in abundance 
according to E. Marchand, by submitting to distillation in a retort, a so- 
lution of chloride of lime and caustic ammonia. — Jour, de Chim. and 
Chem. Gaz. 
Preparation of Carbonate of Potash free from Silica from ordinary Pearl 
Ash. — One pound of peail ash is dissolved in one pound of rain water, 
an d four ounces of finely pulverized vegetable charcoal are added to it; it 
is left for twenty-four hours, being frequently stirred and then filtered. 
On evaporation and saturation with an acid it will be found not to con- 
tain a trace of silica which is otherwise so difficult to remove. — Jour, 
fur Prakt. Chem, and Chem. Gaz. 
