io MATER i A MEDIC A AND THERAPEUTICS. 



pharmacy. This subject demands special considera- 

 tion here. 



Most of the materise medicse possess such 

 characters that it is absolutely necessary to pre- 

 pare them for administration. Thus, if we take, 

 as examples, Sulphur, one of the elements ; Potassii 

 lodidum, a crystalline salt ; Chloroformum, a liquid 

 compound of chlorine and formyl ; Colocynthidis 

 Pulpa, the dried pulp of a fruit; Jalapa, a tuber; 

 and Cantharis, a dried beetle ; it is manifest that 

 few of these can be brought into useful contact 

 with the body in their native form. Preparations 

 must be made from them, and for several reasons we 

 must have a variety of preparations. First, as we 

 have just seen, substances are very various ; secondly, 

 a substance may contain several active principles, 

 soluble in different media, which it may or may not 

 be desirable to extract together or separately ; thirdly, 

 we constantly wish to obtain combinations of drugs, 

 so as to increase, diminish, or otherwise modify the 

 action of each, or to obtain combined action ; fourthly, 

 we must provide for variety of administration or 

 application, externally or internally, to act on a part 

 or to enter the blood by any of the methods of ex- 

 hibition to be presently described ; and we must be 

 ready to meet the tastes and fancies of patients witli 

 respect to pills, powders, etc., as well as the necessities 

 of circumstances. 



The following is a list of the different kinds of 

 preparations in the British Pharmacopoeia. A com- 

 plete list of each will be found in the synoptical tables 

 at the end of the volume. 



Aceta, Vinegars, are extractive solutions in acetic 

 acid (not vinegar). 



Aquae, Waters, are very weak simple solutions of 

 volatile oils in distilled water, obtained by distilling 

 the vegetable products or the volatile oil. Aqua 



