178 
MISCELLANY. 
tion to dryness, and calculating the composition fronn the ignited and 
weighed chloride of potassium. By a mean of two trials, 50.1 per cent, 
was obtained. Walter considers the formula to be K0+5H0, corres- 
ponding with 48.9 per cent, of water. The excess of water he considers 
to be mechanically mixed with the crystals. The crystals dried in vacuo 
are sulphuric, and contain 21.4 per cent, of water, corresponding to 
KO-flHO. Caustic potash melted by a red heat contains 16.05 per cent, 
of water, and is equivalent to KO+HO. Central- Blait, Aug. 1836, 
Essential Oils. All works on pharmacology agree as to the necessity 
of lowering the boiling temperature of water in the preparation of certain 
oils. Mailhe states, that there is no use for this proceeding. He placed 
an ounce of essence of turpentine in eight ounces of distilled water, and 
submitted the whole to distillation. When half of the essence was dis- 
tilled, he placed it in a graduated tube, and marked the quantity of es- 
sence obtained. He made a second experiment similar to the first, but 
with water saturated with common salt. He obtained the same quantity 
of oil as in the first experiment. This experiment appeared remarkable, 
until the appearance of the fine experiments of Rudberg. 
Journal de Pharmacie, 
[The small difference of temperature in these experiments we do not 
consider sufficient to determine the point. Ed. British Ann. of Med. 
Syrups, Some of these are apt to ferment. To prevent it, the boiling 
syrup should be introduced into hot bottles ; the latter then corked, and 
covered with pitch. When the syrup has cooled, it is to be agitated in 
order to mix with it the superior portion liquefied by the vapour of the 
water condensed in the neck of the bottle. It is then to be deposited in a 
cellar, where it will remain without undergoing any change. 
Journal de Pharmacie. 
Calomel obtained by Precipitation, — " Calomel thus obtained is very 
white, and enjoys much more active properties than what is prepared by 
sublimation, which it owes to its extreme division." — Henry and 
Guibourt. 
" When the white precipitate is well washed it has absolutely the 
same composition as calomel ; only it retains almost always a little 
interposed water ; it is very active, because it is much divided." — 
Soubeiran. 
The white precipitate is identical with calomel." — Soubeiran,, Gay ^ 
Lussac and Thenard. 
" Chloride of mercury thus prepared retains always a little common 
salt, which cannot be removed by washing. This small quantity is suffi- 
cient to give solubility to the chloride, and to communicate to it a very 
distinct mercurial taste, by changing it partly into mercury and corrosive 
sublimate; administered internally it excites salivation."— /Jwwia*. 
