The doses given in this work are applicable to adult age unless the contrary is specified; and for the convenience of students, the rules of Gaubins and Young for determining the proper dose of medicines for children are furnished below.

Take the dose for an adult as unity, and for other ages as follows: -

The dose for a person of middle age being 1, or 1 drachm, -

That for a person from 14 to 21 years will be 2/3, or 2 scruples.

" " 7 to 14 " " 1/2, or 1/2 a drachm.

" " 4 to 7 " " 1/3, or 1 scruple.

" a child of 4 " " 1/4, or 15 grains.

" " 3 " " 1/6, or 10 grains.

" " 2 " " 1/8, or 8 grains.

" " 1 year " 1/12, or 5 grains.

The following simple rule by Dr. Young will be found convenient: "For children under twelve years, the doses of most medicines must be diminished in the proportion of the age to the age increased by 12;thus, at two years to 1/7 ; viz:

2 / 1 + 12 = 1 / 7 At twenty-one the full dose may be given." Hence -

For one year, 1 / 1 + 12 = 1 / 13

For two years, 2 / 2 + 12 = 1 / 7

For three years,3 / 3 + 12 = 1 / 5

For four years, 4 / 4 + 12 = 1 / 4

For six years, 6 / 6 + 12 = 1 /3

At twelve years the dose is one half that of the adult. The U. S. Dispensatory states that "To the above rules some exceptions are offered, in particular medicines, which require to be given to children in much larger proportional doses than those above stated. Such as castor oil and calomel, a certain quantity of which will, in general, not produce a greater effect in a child two or three years old than double the quantity in an adult." "Females usually require smaller doses than males, and persons of sanguine temperament than the phlegmatic." The influence of constitutional peculiarities, such as are known as idiosyncrasies, often exist and render patients more than usually Susceptible, or the opposite, to the action of medicines, the doses of which must be regulated accordingly. It should also be remembered that the susceptibility to the action of medicines is diminished by frequent and continued use. In advancing age, the dose is gradually lessened.

Opiates affect children to a greater degree than adults, but children bear larger doses of calomel than adults. Females are more rapidly affected by purgatives than males, and the condition of the uterine system is very important.

Medicinal substances act differently on the same person in summer and in winter, and in different climates. Narcotics act more energetically in hot than in cold climates, and, as a consequence, smaller doses are required in hot climates; the opposite is the case with regard to calomel. Owing to peculiarity of stomach, or rather disposition of body, unconnected with temperament, comparatively mild remedies operate very violently on some individuals.

When administering remedies, the intervals between the doses should be so regulated that the second dose may be taken before the effect produced by the first is entirely effaced. Some medicinal substances, such as mercurial salts, arsenic, etc., are prone to accumulate in the system; and dangerous symptoms may arise if the doses rapidly succeed one another.

The action of some remedies, such as digitalis, elaterium, etc., may continue long after the discontinuance of the agent, and a too powerful effect occur, even by a repetition in diminished doses. Some remedies, such as castor oil, aloes, etc., acquire activity by continued use, hence the dose requires to be diminished.