That no error may occur, I will here append the weights and measures employed in pharmacy, together with the symbols designating each quantity. It is necessary to understand but two measures, as the author has conformed all the solid or liquid quantities to these measures. These are:

1st -- APOTHECARIES' WEIGHT

20 grains (gr.). . . . . . . . . . . . . . . . . . . . . . . 1 scruple.
     8 scruples . . . . . . . . . . . . . . . . . . . . . . . . . 1 drachm.
     8 drachms  . . .. . . . . . . . . . . . . . . . . . . . . . 1 ounce.
    12 ounces (-3). . . . . . . . . . . . . . . . . . . . . . 1 pound (lb).

The doses of powders, extracts, and all such that are not fluid are intended to correspond with this weight.

2d -- APOTHECARIES' MEASURE

  60 minims  . . . . . . . . . . . . . . . . . . . . . . 1 fluid drachm.
    8 fluid drachms  . . . . . . . . . . . . . . . . .  1 fluid ounce.
  16 fluid ounces . . . . . . . . . . . . . . . . . .   1 pint.
    8 pints  . . . . . . . . . . . . . . . . . . . . . . . . 1 gallon (cong.).

The quantities of all fluids mentioned in this book agree with this measure, though the word fluid or the symbol (f) is omitted in most instances.

It is not to be supposed, however, that in all families measuring graduates are to be found; hence a comparison of these measure with tea, dessert, and table spoons, etc., becomes necessary to simplify the fluid measure. The weight of any quantity I should always advise to be correctly ascertained by scales:*

* The weights used in the British Pharmacopoeia are the Imperial or avordupois pound, ounce, and grain, and the terms drachm and scruple, as designating specific weights, are discontinued. The ounce contains 437 ½ grains, and the pound 7,000 grains. The Imperial Measure contains 8 fluid drachms to the ounce, 20 fluid ounces to the pint, and 8 pints to the gallon.

Comparison

A drop corresponds with a minim.

A teaspoonful corresponds with a fluid drachm.

A dessertspoonful corresponds with a three fluid drachms.

A tablespoonful corresponds with a one-half fluid ounce.

A wineglassful corresponds with a two fluid ounces.

A teacupful corresponds with a gill.

In the body of this work the quantity has been stated, with but few exceptions, in which each medicine must ordinarily be given to produce its peculiar effects upon the adult patient. But there are circumstances which modify the dose, and demand attention, the most important of which is the age; hence the following table, exhibiting the dose proportioned to the age, should receive careful reference in domestic practice:

Table

The dose for a person of age being 1 or 1 drachm.

That of a person from 14 to 21 years will be  2/3 or 2 scruples.
      7 to 14 years will be  ½ or ½ drachm.
       4 to 7 years will be 1/3 or 1 scruple.
       of 4 years will be 1/4 or 15 grains.
       of 3 years will be 1/6 or 10 grains.
       of 2 years will be 1/8 or 8 grains.
       of 1 years will be 1/12 or 5 grains.
       of ½ years will be 1/15 or 4 grains.

The following rule, however, is a little more simple:

For children under 12 years the dose of most medicines must be diminished in the proportion of the age to the age increased by 12; thus, at two years the dose will be 1/7 of that for adults, viz.:

2 / 2+12 = 2/14 or 1/7; at 4, it will be 4 /4+12 + 4/16 or 1/4.