The merchants’ powder, before it is received into the government service, is tried against powder of the same kind made at the royal mills; and it is received if it gives a range of ¹⁄₂₀ less than the king’s powder with which it is compared. In this comparison both sorts are tried on the same day, and at the same time, and under exactly the same circumstances.
The proof of fine grained, or musquet powder, is with a charge of 4 drams from a musquet barrel, to perforate with a steel ball a certain number of ¹⁄₂ inch wet elm boards, placed ³⁄₄ inch asunder, and the first 39 feet 10 inches from the barrel: the king’s powder generally passes through 15 or 16, and restoved powder from 9 to 12. The last trial of powder is by exposing about 1 pound of each sort, accurately weighed, to the atmosphere for 17 or 18 days; during which time, if the materials are pure, it will not increase any thing material in weight, by attracting moisture from the atmosphere.
In this exposure 100 lbs. of good gunpowder should not absorb more than 12 oz. or somewhat less than one per cent.
Different modes of trying gunpowder have been adopted. A ready one is, to lay two or three small heaps on separate pieces of writing paper, and fire one with a red hot wire. If the flame ascend quickly, with a good report, leaving the paper free from white specks, and not burnt into holes; and at the same time the other heaps be not fired by the sparks, the powder is well made, and the ingredients are good.
There are experiments which seem to show, that gunpowder is stronger in the fine impalpable form, than when granulated. This appears to be true with regard to gunpowder originally made, or pounded till it assumes that form; but it may be doubted, whether it have any foundation in general, or indeed that the greater strength depends at all upon this form.
British Powder Marks.—The different sorts of powder are distinguished by the following marks on the heads of the barrels.
| No. | ¹⁄₂ | - | Cylinder | - | Marked in Red. | ||
| L | G | ||||||
| —— | |||||||
| No. | 2 | - | Cylinder | ||||
| S | G | ||||||
| —— | |||||||
| No. | 3 | - | Cylinder | ||||
| F | G | ||||||
| —— | |||||||
| S A | —The dust from No. 3, and F G cylinder. |
| R A | —For rifle arms. |
| ⁴⁄₇ Cylinder | - | mixed—Marked white L G. | |
| ³⁄₇ Restoved |
L G or F G in blue, is powder made of pitcoal.