wishes to draw special attention to the quantity; in both these cases the 

 Arabic numerals are used. Further the "i's" in the Roman numerals 

 should have a dash above the letter and the dot should be carefully and 

 distinctly written above the dash, so that they may be counted in con- 

 firmation of the number of strokes below the dash, should any question 

 arise. 



Abbreviations should be used with the greatest care and only such as 

 are certain to be understood. For example such abbreviations, as "chlor'' 

 which might mean chloral, chloroform, chloridum, or as "hyd" which 

 might stand for hydrargyrum, hydras, or hydrochloridum, are not per- 

 misssible. The usual abbreviations for common words will be found in 

 the vocabulary. 



Were the above prescription written in the metric system it would be 

 as follows (in order to fill a standard bottle of 150 c.c. it has been recal- 

 culated and now contains 42 doses). 



!$ Gm. vel. c.c. 



Potassii Acet 41.5gms. ^j ( 41 



Liq. Ammon. Acet 17.5 c.c. 17 



Spt. .Eth. Nit 10. 25 c.c. f 1 10 



Infus. Buchu ad 150.00 c.c. [ 150 



.50 

 50 

 25 

 00 



The quantities are as a rule written in Arabic numerals, and the measure 

 if the prescription be not written on paper with a heading as shown on 

 the right follows the numerals as is shown on the left. Fractions are 

 always written as decimals and again paper as printed on the right with a 

 perpendicular line to distinctly mark the decimal point is a great advantage 

 and a great safe-guard. Such prescriptions when read are commonly 

 read in English and not in Latin. 



The mathematics involved in prescription writing is not more difficult 

 than is the grammar. Two points must first be decided, (1) For how 

 many days and how many doses a day are you going to give the medicine? 

 Taking the case used above as an illustration, we will suppose that you 

 have decided to give three doses a day for a period of ten days, in all thirty 

 doses. (2) How much of each ingredient do you wish to give at each 

 dose? We will suppose that you intend to give 15 grs. of Potassium Ace- 

 tate, 7 min. of Solution of Ammonium Acetate, 4 min. of the Spirit of 

 Nitrous Ether, and some of the Infusion of Buchu (the latter is a compara- 

 tively inactive flavouring ingredient and may be given in considerable 

 doses). You have already only 11 mins. of fluid; the acetate is very soluble 

 and would readily dissolve in 30 min. therefore there is no need to give a 

 larger dose than 1 fl. dr. The total quantity that you will want is 30 fl. dr. 

 :32 fl. dr. make 4 fl. oz., which is the size of a standard bottle. The pre- 

 scription will then be written for 32 doses, or of Acetate of Potassium 32 x 

 15 grs. = 480 grs. one Troy ounce; of Solution of Ammonium Acetate, 

 32 x 7 = 224 min. or approximately 3>^ fl. dr. (210 min.); of Spirits of 



118 



