The merchants’ powder, before it is received into the king’s service, is tried against powder of the same kind made at the king’s 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 ½ inch wet elm boards, placed ¾ 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 anything 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. _Powder Marks._—The different sorts of powder are distinguished by the following marks on the heads of the barrels. --------+-------------+----------------------- Nᵒ. ½ | | L G | Cylinder | --------+-------------+ Nᵒ. 2 | | S G | Cylinder | Marked in Red. --------+-------------+ Nᵒ. 3 | | F G | Cylinder | --------+-------------+----------------------- 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. RS Nᵒ. ½ L G Marked in yellow, Nᵒ. 3 F G is restoved. The _red_ L G, F G, or S G, denotes powder entirely made of the cylinder charcoal, and is that which is now always used on service. The white L G being a mixed powder, is not so uniform as the other, and is therefore generally used in filling shells, or for such other purposes as do not require much accuracy. All powder for service is mixed in proportions according to its strength, so as to bring it as much as possible to a mean and uniform force. _French Gunpower._—The French proof ball is of brass, and weighs 60 lbs. French: the diameter of the mortar 7 inches 9 points, or ¾ of a line, and has one line of windage. The chamber holds exactly 3 ounces; and their best powder must give a range of 90 toises, and their restoved powder a range of 80 toises, to be received into the service. But the powder they now make, when new, will give a range of 100 and 120 toises; and Mr. Lombard calculates all his tables from experiments made with powder giving 125 toises with the eprovette.—The above dimensions and weights are all of French standard.