**WEIGHTS AND MEASURES**

- METRIC SYSTEM
- BRITISH AND AMERICAN WEIGHTS AND MEASURES
- APPROXIMATE EQUIVALENTS
- APPROXIMATE LIQUID MEASURES

**THE METRIC SYSTEM****Linear Measures**- The unit is the meter which is the one tenth-millionth part of the meridian quadrant of the earth, the circumference of the earth at the equator being therefore 40,000,000 meters, or 40,000 kilometers, or roughly 25,000 miles. Multiples of the meter are indicated by prefixes derived from the Greek, as follows:
- Meter; decameter, 10 meters; hectometer, 100 meters; kilometer, 1000 meters; myriameter, 10,000 meters.
Fractions of the meter are indicated by prefixes derived from the Latin, as follows:

- Meter; decimeter 1/10 meter; centimeter 1/100 meter; millimeter, 1/1000 meter.
In microscopy, the unit of measure is 1/1000 of a millimeter, called micron or, incorrectly, micromilleter; the prefix micro- properly denotes the one-millionth of the measure to which it is attached, the micron being therefore correctly called micrometer.

**Square Measures**

A square meter, in land measure, is called a centiare; 100 sq. meters = 1 are; 100 ares (10,000 sq. meters) = 1 hectare.

**Cubic Measures or Volumes**

The unit of volume is the cubic decimeter, called a liter; one liter of water weighs practically 1 kilogram. It is divided into the deciliter, 1/10 liter (weight 100 grams); centiliter, 1/100 liter (weight 10 grams); and milliliter (cubic centimeter), 1/1000 liter (weight 1 gram).

Theoretically there are also multiples of the liter: decaliter, 10 liters; hectaliter 100 liters; kiloliter, 1000 liters; practically however, the hectaliter (weight of water 100 kilograms) is the only multiple in use.

**Weights**- The unit of weight is the gram, or gramme, abbreviation gr. (in English speaking countries usually g. or gm. to distinguish it from grain). It is practically the weight of one cubic centimeter of distilled water at its maximum density (4 º C.). Multiples of this unit are designated by prefixes derived from the Greek numerals, as follows:
- Gram; decagram, 10 grams; hectogram, 100 grams; kilogram (abbr. kilo), 1000 grams.

- Fractions of the gram are designated by prefixes, derived from the Latin numerals, as follows:
- Gram; decigram, 1/10 gram; centigram, 1/100 gram; milligram, 1/1000 gram.

2 c.c. or 2 gm., 2. or 2| 1/10 c.c. or 1/10 gm., 0.1 or |1 3/100 C.C. or 3/100 gm., 0.03 or |03 2/1000 C.C. or 2/1000 gm., 0.002 or |002 1 35/100 C.C. or 1 35/100 gm., 1.35 or 1|35

In the United States the weights used in prescription writing and the compounding of drugs are those of the apothecaries' system; the weights of the British Pharmacopeia are those of the avoirdupois system. In both, the weight of the grain is the same, but the drachm, ounce, and pound differ.

---Troy Weights--- pound - ounces - pennyweights - grains 1 = 12 = 240 = 5760 1 = 20 = 480 1 = 24

---Apothecaries' Weights (U.S.P.)--- pound - ounces - drachms - scruples - grains 1 = 12 = 96 = 288 = 5760 1 = 8 = 24 = 480 1 = 3 = 60 1 = 20

---Avoirdupois Weights (B.P.)--- pound - ounces - drachms - grains 1 = 16 = 256 = 7000 1 = 16 = 437.5 1 = 27.34375To convert apothecaries' ounces to avoirdupois, subtract 1/11 to convert avoirdupois ounces to apothecaries', add 10 per-cent. These are approximate equivalents.

---LIQUID MEASURES--- United States Apothecaries' Measures fluid fluid gal - qts - pts - ounces - drachms - minims 1 = 4 = 8 = 128 = 1024 = 61440 1 = 2 = 32 = 256 = 15360 1 = 16 = 128 = 7680 1 = 8 = 480 1 = 60

---Imperial Apothecaries' Measures--- fluid fluid gal - qt - pts - ounces - drachms - minims 1 = 4 = 8 = 160 = 1280 = 76800 1 = 2 = 40 = 320 = 19200 1 = 20 = 160 = 9600 1 = 8 = 480 1 = 60The minim, fluidrachm, and fluidounce of the U.S. apothecaries' measure are slightly larger than the corresponding denominations in the Imperial (British) measure; the pint, quart, and gallon, on the other hand, are materially smaller.

U.S. Imp. Imp. U.S minim, fluidrachm, fluidounce, 1 = 1.0406 1 = 0.9609 pint, quart, gal. 1 = 0.8325 1 = 1.2011

One kilometer = 5/8 mile or 3281 feet; 8 kilometers = 5 miles; 1 meter = 39 inches; 1 centimeter = 2/5 a inch; 1 millimeter = 1/25 inch or 1/2 line; 1 micron = 1/25000 inch.

One mile = 1 3/5 kilometers; 1 yard = 92 centimeters; 1 foot= 30.5 centimeters; 1 inch = 26 millimeters; 1 line = 2 millimeters.

To convert kilometers to miles, multiply by 5 and divide by 8; to convert miles to kilometers multiply by 8 and divide by 5.

To convert meters to yards, multiply by 70 and divide by 64; to convert yards to meters multiply by 64 and divide by 70.

To convert centimeters to feet, multiply by 10 and divide by 307; to convert feet to centimeters multiply by 307 and divide by 10.

To convert millimeters to inches, multiply by 10 and divide by 254; to convert inches to millimeters multiply by 254 and divide by 10.

To convert grams to ounces divide by 30; to convert ounces to grams, multiply by 30.

To convert grams to drachms, divide by 4, to convert drachms to grams multiply by 4.

To convert grams or fractions of a gram to grains, multiply by 15; to convert grains to grams, divide by 15.

To convert centigrams to grains, divide by 6; to convert grains to centigrams, multiply by 6.

To convert milligrams to grains, divide by 60; to convert grains to milligrams, multiply by 60.

**Fluid Measures**

One liter = 1.76 imperial pints or 2.1 U.S. pints; 1 cubic centimeter = 17 minims (B.P.) or 16 1/4 minims (U.S.P.).

One imperial gallon = 4.55 liters; 1 U.S. gallon= 3.79 liters; 1 imperial pint = 568 cubic centimeters; 1 U.S. pint = 473 cubic centimeters; 1 fluid ounce (B.P.) = 28.4 cubic centimeters; 1 fluidounce (U.S.P.) = 29.5 cubic centimeters; 1 fluid drachm (B.P.) = 3.5 cubic centimeters; 1 fluidrachm (U.S.P.) = 3.7 cubic centimeters, 1 minim = 0.065 cubic centimeter.

To convert liters to imperial pints, multiply by 88 and divide by 50; to convert liters to U.S. pints, multiply by 21 and divide by 10; to convert imperial pints to liters, multiply by 50 and divide by 88; to convert U.S. pints to liters, multiply by 100 and divide by 21.

To convert cubic centimeters to fluid drachms divide by 4; to convert fluid drachms to cubic centimeters multiply by 4.

To convert cubic centimeters, or fractions thereof, to minims, multiply by 15; to convert minims to cubic centimeters, divide by 15.

**APPROXIMATE LIQUID MEASURES**

In America a teaspoonful is reckoned as 1 fluidrachm, or 4 c.c.; a dessertspoonful as 2 fluidrachms, or 8 c.c.; a tablespoonful as half an ounce, or 16 c.c. In Great Britain a teaspoonful is regarded as approximately the equivalent of 5 c.c. (80 minims); a tablespoonful as three teaspoonfuls or 15 c.c. (240 minims).

A wineglassful is 2 fluidounces, or 60 c.c.; a teacupful = 2 wineglassfuls, 4 fluidounces, 125 c.c.; a tumblerful = 4 wineglassfuls, 8 fluidounces, half a pint, 250 c.c.

A drop is a measure of very uncertain quantity, varying in size not only according to the nature of the liquid but also according to the shape of the container and its aperture, from which the drop falls, so that the number of drops in the fluidrachm may vary from 41 to 172. The internationally official drop of distilled water, at 15 º C., numbers 20 to the gram.