PHARMACEUTICAL PREPARATIONS. 
finally remove it to a cold water bath and stir constantly 
until when on cooling it begins to thicken. 
[The author regrets that this formula is so troublesome, 
but he conceives the manipulation stated to be quite neces- 
sary to the production of a handsome ointment. He is not 
certain that the entire removal of the deutoxide of nitrogen 
from the mercurial solution is essential to the process, but 
inclines to believe that it is. He further states that on the 
addition of the cold mercurial solution, the temperature falls 
to 1 65° F., and that if the heat is continued much above 190° 
at first, the re-action will be so violent as to cause the oint- 
ment to run over the vessel, unless this is very large : the 
resulting ointment being dark coloured and granular. — Ed.] 
Pills of Copaiba. This preparation is sometimes difficult 
to obtain in a " pilular mass." In following the directions 
of the Pharmacopoeia, the mixture of copaiba with one six- 
teenth of its weight of magnesia, after standing a whole day, 
remained semi-fluid ; it was then stood aside for a month 
without acquiring a thicker consistence. In order to satisfy 
myself of the conditions necessary to the success of the ope- 
ration, a series of experiments was undertaken, the results 
of a few of which were as follows, viz : 
1st. A portion of copaiba of the consistence of syrup, (the 
same kind as that used above,) was heated till ebullition com- 
menced, when it was removed from the fire, and the mag- 
nesia, one sixteenth of its weight, yet warm from recent 
calcination, was stirred in ; after several hours it had be- 
come a good deal harder than the first lot, although not of a 
consistence proper for forming into pills, and at the end of 
two days its firmness had not increased. It was then re-heat- 
ed, another portion of freshly calcined magnesia,equal to the 
first was stirred in, and at the expiration of four hours the 
mixture had concreted into a good pilnlar mass. 
2d. A portion of very old and thick copaiba was heated 
till ebullition commenced, when one eighth of its weight of 
hot recently calcined magnesia was stirred into it. It solid- 
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