The above weights are usually adopted in formulas.
All chemicals are usually sold by
Avoirdupois Weight
| 27 11/32 grains = | 1 drachm = | 27 11/32 grains |
| 16 drachms = | 1 ounce = | 437 1/2 grains |
| 16 ounces = | 1 pound = | 7,000 grains |
Precious metals are usually sold by
Troy Weight
| 24 grains = | 1 pennyweight = | 24 grains |
| 20 pennyweights = | 1 ounce = | 480 grains |
| 12 ounces = | 1 pound = | 5,760 grains |
NOTE.—An ounce of metallic silver contains 480 grains, but an ounce of nitrate of silver contains only 437 1/2 grains. {759}