80 PRESCRIPTION WRITING 



We stated that 3i. = 4 Gm. It follows that §i. would equal 32 Gm. As 

 a factj 5i. apothecaries' weight, is equivalent to a trifle less than 4 Gm. ; 

 and an ounce, apothecaries' weight, is usually considered equal to 30 Gm. 

 (exactly 31.10 Gm.) for the sake of convenience. A fluid ounce in wine 

 measure is precisely equivalent to 29.57 cc. We have here another rea- 

 son why both solid and fluid ounces should be valued at 30 Gm. or cc. 

 Although it is the custom to regard the minim of liquid as the equivalent 

 of one grain, it is inexact. An apothecaries' ounce weighs 480 gr. ; a 

 fluid ounce of wine measure weighs 457 gr. Multiples of grams or cubic 

 centimeters may be designated as such, instead of using the technical 

 terms. It is perfectly proper to speak of 100 Gm. as one hundred grams, 

 although technically equal to a hectogram. .1 Gm. may be called one- 

 tenth gram, although technically a decigram. Similar remarks apply to 

 cc, yet 1,000 cc. (approximately 1 quart) equal one liter, and this term 

 is in common use. In the ninth (1916) edition of the U. S. Pharmacopeia 

 the British term "mil" (abbreviation of milliliter — mille, Latin for one 

 thousand and in the combining form usually meaning one one-thousandth) 

 or the thousandth part of a liter is used instead of the more cumbersome 

 cubic centimeter. Thus the word "mil" is rapidly coming into use in 

 scientific literature to replace the abbreviation "cc." In time it may 

 wholly replace it in medical literature but for the present it is necessary 

 for the veterinary student to be familiar with both terms. 



Note that the abbreviation for gram, Gm., is capitalized and the 

 abbreviation for grain, gr., is not. 



Rules for Forming the Genitive Case in Prescription Writing. 



The Latin names of drugs, as we learn them, when consisting of a 

 single word, are in^the nominative case. For example: oleum, an oil. 

 The genitive case of a Latin word means of (the word), and is equivalent 

 to the English possessive. Thus the Latin name oleum lini, consists of 

 two words. The first, oleum, is the Latin nominative for oil, and the sec- 

 ond word, lini, is the Latin genitive of the word meaning linseed. The 

 name signifies, then, oleum (oil) and lini (of linseed). In writing pre- 

 scriptions it is usually essential to put the Latin name of the drug in the 

 genitive case, following the use of the heading ]^, standing for the Latin 

 imperative Recipe, meaning in English, Take. 



For example: 



Potassi nitratis gi. 



Literally translated this means: 

 Take 



Of potassium nitrate, ounce 1. 



There is only one other case which is used in writing prescriptions 

 (the accusative), but this can be avoided by using abbreviations in "the 

 few instances in which it should be employed. The following rules can 

 be memorized (with their exceptions) in order to form the genitive case 

 (singular) : 



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