isisisThe basic unit of weight in the metric systemthe gram. NOTE: The abbreviation for gram“g.”The basic unit of volume in the metric systemthe liter, abbreviated “1.”The basic linear unit of the metric system isthe meter, abbreviated “m.”By using the prefixes deka, hecto, and kilo formultiples often, one hundred, and one thousandbasic units, and the prefixes micro, mini, centi,and deci for one ten thousandth, one thousandth,one hundredth, and one tenth, you have the basicstructure of the metric system. By applying theappropriate basic unit to the scale of figure 8-1,you can readily determine its proper terms. Forinstance, using the gram as the basic unit ofweight, we can readily see that 10 g would be 1dekagram, 100 g would equal 1 hectogram, and1000 g are called a kilogram. Conversely, goingdown the scale, 0.1 g is then called a decigram,0.01 g a centigram, and 0.001 g is called amilligram. NOTE: In the metric system, no unitsor their abbreviations are capitalized.THE APOTHECARY SYSTEMAlthough fast becoming obsolete, theapothecary system is still used and must be takeninto consideration. It has two divisions ofmeasurement: weight and volume. The basic unitof weight is the grain, abbreviated gr, and nevercapitalized; and the basic unit of volume is theminim.THE AVOIRDUPOIS SYSTEMThis system is the one used in the United Statesfor weight only and is used in commercial buy-ing and selling. The pound as we know it whengoing to the market is the 16-ounce pound of theavoirdupois system. The basic unit of the avoir-dupois system is also the grain.TABLE OF WEIGHTS ANDMEASURESTable 8-1 is a table of weights and measures;it should be thoroughly studied and memorized.CONVERTING WEIGHTS ANDMEASURESOccasionally there are times when it will benecessary to convert weights and measures fromone system to another, either metric to apothecaryFigure 8-1.—Metric system.or vice versa. Since patients can hardly be expectedto be familiar with either system, always translatethe dosage directions on the prescription into ahousehold equivalent that they understand.Therefore, the household measurements arestandardized, assuming that the utensils are com-mon enough to be found in any home. Table 8-2is a table of household measures, with their metricand apothecary equivalents.Table 8-2.—Table of metric doses with approximateequivalents8 - 3