The usual method pursued by medical men in calculating the doses of medicine for children is to average the dose in proportion to their approximate weight or to figure out a dose upon the assumption that at 12 years of age half of an adult dose will be about right. Calculated on this basis the doses for those under 12 will be in direct proportion to the age in years plus 12, divided into the age. By this rule a child 1 year old should get 1 plus 12, or 13, dividing 1, or 1/13) of an adult dose. If the child is 2 years old it should get 2 plus 12, or 14, dividing 2, or 1/7 of an adult dose. A child of 3 years should get 3 plus 12, or 15, dividing 3, or 1/5 of an adult dose. A child of 4 should get 4 plus 12, or 16, dividing 4, or 1 of an adult dose.

As both children and adults vary materially in size when of the same age the calculation by approximate weights is the more accurate way. Taking the weight of the average adult as 150 pounds, then a boy, man, or woman, whatever the age, weighing only 75 pounds should receive only one-half of an adult dose, and a man of 300 pounds, provided his weight is the result of a properly proportioned body, and not due to mere adipose tissue, should be double that of the average adult. If the weight is due to mere fat or to some diseased condition of the body, such a calculation would be entirely wrong. The object of the calculation is to get as nearly as possible to the amount of dilution the dose undergoes in the blood or in the intestinal contents of the patient. Each volume of blood should receive exactly the same dose in order to give the same results, other conditions being equal.


See Veterinary Formulas.