2. For the use of apothecaries and for selling drugs retail:
(a) MEASURES OF WEIGHT
- 20 grains = 1 scruple (
- )
- 3 scruples = 1 drachm (
- )
- 8 drachms = 1 Apothecaries’ ounce (oz. Apoth.)
(b) MEASURES OF CAPACITY
- 60 minims (min.) = 1 fluid drachm (fl. dr.)
- 8 fluid drachms = 1 fluid ounce (fl. oz.)
Of the Apothecaries’ measure of weight, the grain is the same as the Imperial grain; and the Apothecaries’ ounce contains 480 grains, like the Troy ounce. But, of the measures of capacity, the Apothecaries’ drachm is not the same as the Imperial dram, and the two words are spelt differently. A fluid ounce of distilled water at a temperature of 62° Fahrenheit is equal in weight to the Imperial ounce (437.5 grains), and the fluid drachm (54.6875 grains) is equal in weight to two Imperial drams.
ELECTRICAL MEASURES
It is customary to express electrical measures in terms of the centimeter, the gramme, and the second, and the value of the units {156} has been fixed by international agreement. The principal units, as described in the Order in Council of January 10, 1910, are as follows:
The OHM, the unit of resistance, is the resistance offered to an unvarying electric current by a column of mercury, at the temperature of melting ice, 14.4521 grammes in mass, of a constant cross-sectional area, and of a length of 106.3 centimeters.
The AMPERE, the unit of current, is the unvarying electric current which, when passed through a solution of nitrate of silver in water, deposits silver at the rate of 0.001118 of a gramme per second.