Liquid medicines are always measured by the following table:
60 minims......... \ / 1 fluid drachm.
8 fluid drachms | are | 1 fluid ounce.
20 fluid ounces... | contained | 1 pint.
8 pints.......... / in \ 1 gallon.
And the signs which distinguish each are as follows:--c. means a
gallon; o a pint; _fl_ [*ounce], a fluid ounce; _fl_ [*drachm], a
fluid drachm; and m, a minim, or drop. Formerly drops used to be
ordered, but as the size of a drop must necessarily vary, minims are
always directed to be employed now for any particular medicine,
although for such medicines as oil of cloves, essence of ginger, &c.,
drops are frequently ordered.