663. Measures—Liquid
Liquid medicines are always measured by the following table:
| 60 minims | are contained in | 1 fluid drachm |
| 8 fluid drachms | are contained in | 1 fluid ounce |
| 20 fluid ounces | are contained in | a pint |
| 8 pints | are contained in | 1 gallon |
And the signs which distinguish each are as follows:
| c | a gallon |
| o | a pint |
| fl. | a fluid ounce |
| fl. | a fluid drachm |
| 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.
664. Specific Measuring Vessels
In order that medicines may be measured accurately, there are graduated glass vessels for measuring ounces, drachms, and minims.