PRESCRIPTION WRITING 75 



Approximate Equivalents of Wine Units in Domestic Measures. 

 Teaspoon ^=:: 3i-ii. = 5 mils (or cc.) 



Dessertspoon ■= 3ii. ^ 10 mils (or cc.) 

 Tablespoon = §ss. ■= 15 mils (or cc.) 

 Cup = giv. = 120 niils (or cc.) 



Tumbler = Bviii. = 240 mils (or cc.) 



There are usually about six teaspoonfuls to the fluid ounce. It is a 

 good. plan to have some regard for the size of vials generally kept by 

 druggists, and to write for a quantity to fill the bottle. The bottles com- 

 monly in use in human and canine practice are the 2 and 4 dram; the 

 1, 2, 3, 4, 5, 6, 8, 12, and 16 ounce. 



The 2-dram bottles are useful for measuring the dose of fluid extracts 

 for horses ; the 3-ounce bottle is convenient in writing prescriptions in the 

 metric system for dogs, as it holds approximately 100 mils. The 4-ounce 

 bottle is the common size, employed in canine practice, containing 24 

 doses of one teaspoonful each. The I/2 pi'^t and pint bottles are more 

 appropriate for larger animals. 



The Metric System. 



The metric system will be described, because it is tlie universal sys- 

 tem employed in scientific writings, and is now official (employed in the 

 U. S. Pharmacopeia). It is based on the fact that a uniform, unchange- 

 able standard is employed as the unit of all measures, whether of weight, 

 capacity or area. . This standard is the ten-millionth part of the distance 

 from either pole to the equator, and is denominated a meter (39.371 

 inches), and is the standard of length. The cube of 0.1 of a meter is 

 taken as the unit of capacity and called a litre (2.1135 pints). The 

 weight of water at its greatest density, 4° C. (39.2° F.), which this cube 

 will contain, is termed a kilogram (2.2046 lbs. avoirdupois), and is the 

 unit of the measure of weight of ordinary commerce. 



Metric Diagram 



The weight of water that the small cube will contain is one gram. 

 This is the unit of weight of the metric system. Since the large cube will 

 contain one liter the small cube will contain one one-thousandth of a liter 

 or one milliliter (abbreviated 1 mil). But for prescriptions and other 

 small weighings lesser units than the kilo and liter are required and 

 therefore the cube of one-hundredth of a meter is taken and the weight 

 of water which this cube holds is recognized as the unit of weight and 

 called a gram (15,432, grains). The quantity of water contained in the 

 cube of one-hundredth of a meter is used as a unit in measuring capacity 

 in chemical and pharmaceutical practice and termed a cubic centimeter. 

 The multiples of these measures, proceeding in decimal progression, are 

 distinguished by Greek numerals as prefixes, i.e., Deca-10, Hecto-100, 

 Kilo-1000. The subdivisions of the unit are represented by the Latin 

 prefixes, as deci-0.1, centi-0.01, milli-0.001. Hence, using the gram as 

 the unit, we can arrange a table as follows: 



Kilogram Kg. = 1,000 grams = 1,000.0 

 Hectogram Hg. = 100 grams = 100.0 



Decagram Unitized by MiMXifBii^ <== 10.0 



