MOHR AND REDWOOD'S PRACTICAL PHARMACY. 221 
ness. Emetic tartar, antimonial powder, and many 
other substances of this kind will come into the same class. 
Conserve of hips is a very useful excipient for this class of 
substances, at least for those of them which are not decom- 
posed by the vegetable acid contained in the conserve. It 
answers very well for making calomel pills, the pills retain- 
ing a soft consistence for a great length of time. In some 
cases crumb of bread, treacle, or extract of liquorice, may 
be substituted for it. Pills made with crumb of bread, how- 
ever, become very hard after being kept for some time. 
Castor oil is an excellent excipient for the compound calo- 
mel pills of the Pharmacopoeia. The mass, when made 
with this excipient, will retain a uniformly good consistence, 
which is not the case when treacle is used. 
<{ Crumb of bread is frequently employed as the excipient 
for creasote, and for some active agents, as croton oil and 
nitrate of silver, which are administered in very small doses. 
" The effect, in some cases, of a judiciously selected ex- 
cipient is quite surprising, and the pharmaceutical student 
would find that the subject offers an interesting field for 
further experiment. When it is found that a substance so 
apparently ill adapted for making into pills as a liquid 
oleo-resin, may be rendered fit for that purpose by the addi- 
tion of a very small quantity of magnesia or lime, and that 
fatty substances, such as mercurial ointment, will assume a 
pilular consistence on the addition of a little phosphate of 
lime, he may hope to find equally simple means for subject- 
ing other apparently intractable substances to the required 
purpose. 
"In all cases it is very important that the whole of the 
ingredients of the pill-mass should be perfectly mixed and 
incorporated. When small quantities of active medicines 
form part of the ingredients, the precaution already alluded 
to in reference to the preparation of powders should be ob- 
served, that is, that such substances should be placed on the 
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