To get a ¹/₁₀₀ of a grain dose of any drug out of a solution of 60 minims containing ¹/₃₂ of a grain of that drug, compute as follows:

Rule.—Multiply the quantity of the solution on hand in minims by a number indicating the fractional amount of the drug therein contained, and divide by a number indicating the fractional amount of the drug desired.

In 20 parts ofsolutionwe have1 part ofcarbolic acid.
In  1 part¹/₂₀ “
In100 parts100 × ¹/₂₀ = 5 pt.
40 parts contain1 part ofcarbolic acid.
 1 part contains¹/₄₀ “
So that ¹/₄₀ solution is a 2½ per cent. carbolic acid solution.

ACTION, USES, AND DOSES OF
THE MOST IMPORTANT DRUGS.

Acetanilid.—This substance, a derivative of anilin, is used to lower temperature; to relieve headaches and neuralgic pains; and to allay spasm, as in chorea and whooping-cough.

Toxic doses cause lividity, cold sweats, ringing in the ears, and heart failure.

The dose is from 5 to 10 grains (0.3-0.6 gm.).