152 PHILADELPHIA COLLEGE OF PHARMACY. 
calcination, ignition, fusion, reduction, carbonization, inci- 
neration, &c, are conducted. On the theory of the forma- 
tion of crystals and their geometrical relations, he would 
have little to say, but the means of controlling the cooling 
of saturated solutions of crystallizable matter, of gradual 
evaporation, and the shape and position of the vessels in 
obtaining good crystallizations, he would probably fully ex- 
plain. 
The division of drugs by bruising, grinding, rasping, &c, 
as preliminary to the important operation of pulverization, 
which latter in all its phases, together with the mortars, 
mills, sieves and other instruments which are employed in 
accomplishing it, and the various precautions necessary in 
effecting the proper division of drugs, would be expatiated 
upon and applied. 
The means of extracting the activity of substances by 
maceration and displacement, as in the preparation of ex- 
tracts, tinctures, wines, syrups, &c, would, we doubt not, 
receive a large share of attention, inasmuch as these classes 
of preparations embrace very many of the most important 
medicinal agents. 
After giving a thorough examination to all the elemen- 
tary operations of a Pharmaceutical Laboratory, the offici- 
nal preparations of the Pharmacopoeia in classes, would 
afford a wide field for illustration, in which the knowledge 
communicated in the previous lectures could be profitably 
applied. Extemporaneous Pharmacy, or the knowledge 
required in compounding prescriptions, is so various in its 
character, is effected by so many unforseen circumstances, 
and requires such constant presence of mind in its applica- 
tion, that it can only be properly acquired by long prac- 
tice in the shop; yet by a judicious selection of difficult 
prescriptions, and of cases where, from professional igno- 
rance orcarelessness,it becomes the duty of the Apothecary, 
either to pause until an explanation has been had of the 
Physician, or to assume the responsibility of a change in the 
