Pharmacy, or the preparation of substances of definite chemical compo- 

 sition, such as salts, acids, alkaloids, etc. This branch has now passed 

 entirely out of the hands of the practising physician and almost entirely 

 out of those of the practising pharmacist. Secondly, Galenical Pharmacy, 

 or the preparation for administration in the form of medicine of drugs of 

 indefinite chemical composition, which are, as a rule, products of plant or 

 animal life and usually intimate mixtures of many chemical substances. 

 Galenical pharmacy has now been almost entirely abandoned by the 

 physician and only some of the simplest procedures are now carried out 

 by him. The practising pharmacist as a rule no longer carries out the 

 more complex galenical procedures but purchases many of his stock of 

 galenicals from the larger pharmaceutical houses. Thirdly, Dispensing, 

 Magistral Pharmacy, or the preparing and putting up in suitable form for 

 the patient the drugs or their galenical preparations ordered by the 

 physician. 



"POSOLOGY" is the branch of medical science that deals with the doses 

 of drugs and their preparations. The knowledge of this subject is of the 

 utmcst importance for the physician. 



"PHARMACOLOGY" is the science that deals with the action of drugs 

 upon the animal body. This science is often termed "PHARMACODY- 

 NAMICS"; the term "Pharmacology" being then used in a broader sense to 

 include pharmacy, pharmacology, pharmacognosy, and posology. ' ' THER- 

 APEUTICS" is the art of applying the knowledge of these four sciences to 

 the treatment of disease. 



The Pharmacopoeia also prescribes the systems of weights and measures, 

 which are to be used in the operations of pharmacy. The older system, 

 the IMPERIAL SYSTEM, is still almost exclusively used for Magistral Phar- 

 macy, in spite of its obvious disadvantages, and in it alone the doses are 

 given in the Pharmacopoeia Britannica. 



MEASURES OF MASS OF THE IMPERIAL SYSTEM. 



Metric 

 Equivalent. 



1 grain abbreviated gr 64.7987 mgms. 



437.5 grs. 1 ounce.abbreviated Oz. or 5 28.349 gms.v' 



7,000 grs. 16 oz. 1 pound, abbreviated Ib 453.59 gms. 



Very commonly a weight known as a drachm (dr. or 3) equivalent to 

 60 grains (3.8879 gms.) is employed in prescribing and dispensing and 

 more rarely the scruple 9 equivalent to 20 grains. Both these weights are 

 survivals of the Troy system and it is the common practice of pharma- 

 cists in spite of the ruling of the Pharmacopoeia to use in dispensing the 

 Troy ounce of 480 grains, unless there is some indication that the Imperial 

 ounce is intended. (If the sign be used it is customary to dispense 480 

 grains, while if the word ounce be written the Imperial ounce would be 

 dispensed). 



