PREPARATION OF MERCURIAL OINTMENT. 
65 
Only twenty-five grammes, of this substance are required 
to the livre of ointment, and so small a quantity of product 
is not capable of giving injurious properties to a medica- 
ment, which cannot long be preserved from rancidity, and 
which is seldom or never employed except in this state. 
The conditions of a prompt division of the metals are re- 
duced to two : — 1st. To dividing by trituration. 2d. To 
preventing the re-union of the separa ted parts. 
The first condition is always fulfilled ; but the second sel- 
dom, if ever. Indeed, recent lard being deficient in agglu- 
tinative properties, cannot, therefore, retain the mercurial 
powder, and prevent the reunion of its particles. 
Fresh lard is therefore incapable of completely "killing" 
mercury. 
Will it be objected to me, that vigorously continued labor 
is always, in a little time, followed with success ? To this 
I reply, that I have never seen the labor terminated 
before the grease had determined an evident odor of ran- 
cidity. 
But why is this state of alteration favorable to the ex- 
tinction of the metal ? The examination of this very matter 
will serve for a reply. 
That which at once attracts our notice in rancid grease, 
is its consistence. If it be left only until that degree of al- 
teration at which it still possesses a certain softness, it is 
immediately perceived that it has acquired very evident 
agglutinative properties. If it be agitated in the mortar, 
it adheres very firmly to the pestle, and makes a noise simi- 
lar to that made by beating turpentine. 
If, into the midst of this matter thus triturated, a certain 
quanti ty of mercury be poured, the agitation being continued 
the metal will be immediately divided, and the adhesion 
of the grease, which will envelope each of its particles, will 
necessarily prevent their reunion. When we reflect on the 
profound and extensive division which each stroke of the 
pestle operates on a body so fluid as mercury, we shall not 
6* 
