10 PHARMACY 



of a gram and milligrams are used. In the measures of quantity 

 the Liter and milliliter and fractions of them are used. 



In prescription writing only two units, grams and milliliters, 

 are used, abbreviated gm. and mil. In expressing the quantity of 

 drug in a prescription in the metric system, the quantity is always 

 denoted by the Arabic figure placed before the appellation. Trac- 

 tional parts are always converted into decimal fractions. It is not 

 necessary to write grams, or milliliters or their abbreviations, in a 

 prescription because it is understood that the former will be used 

 as the unit of weight and the latter for the unit of measure. 



TABLE OF APPEOXIMATEXY EQUIVALEITT WEIGHTS AND MEASURES 



To convert grains into centigrams, multiply by 6.5. Thus 3 

 grains multiplied by 6.5 equals 10.5 centigrams, or 10 grains equal 

 65 centigrams or .65 grams. To convert centigrams into grains, 

 divide by 6.5. Thus 26 centigrams divided by-6.5 equals 4 grains. 



