Chapter XVI: Part VIII: Gunpowder

1. What are the ingredients in _gunpowder_?

Saltpetre, charcoal and sulphur.

2. What are the proportions?

In the United States, 75 to 76 saltpetre, 14 to 15 charcoal, and 10 sulphur.

England, 75 Saltpetre, 15 Charcoal, 10 Sulphur.
France, 75 “ 12½ “ 12½ “
Prussia, 75 “ 13½ “ 11½ “

3. What is the combustible ingredient?

Charcoal.

4. What is the use of the saltpetre?

It furnishes the oxygen necessary to support a rapid combustion, and to change the whole mass into gas.

5. What is the use of sulphur?

It adds consistency to the mixture and intensity to the flame, besides rendering the powder less liable to absorb moisture.

6. On what does the quality of gunpowder depend?

On the intimate mixture and proper proportions and purity of the ingredients.

7. In what does the manufacture of gunpowder consist?

In pulverizing the ingredients, incorporation, compression, granulation, drying, glazing and dusting.

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8. Explain the method of making gunpowder by the pounding mill.

The charcoal in small pieces is first placed in the mortars, with a quantity of water, and pounded for half an hour; after which the saltpetre and then the sulphur, previously pulverized and sifted, are put in, and the whole well mixed with the hand; it is then pounded in the mortars, and at the end of each hour, the composition is passed from each mortar into the next. At the sixth or eighth change, add half a pint of water; it is then pounded two hours without changing the mortars, in order that it may form into cake. It is then partially dried, and grained in a graining sieve, or passed between wooden rollers. The grains are then sifted to separate those which are too coarse and too fine, and also to separate from each other the different kinds of grains for _cannon_, _musket_, and _rifle_ powder. It is then glazed in large glazing barrels, which make 15 or 20 revolutions in a minute. A charge of 500 lbs. is thus treated for about twenty-four hours. It is then dried either in the open air, or in a drying house. If in the open air, when the sun is too hot, the powder should be covered to prevent the loss of sulphur. It is then _dusted_, by being sifted in fine sieves, or through bolting cloths.

9. What other machines besides the pounding mill are used in pulverizing and incorporating the ingredients of gunpowder?

Rolling barrels, and the cylinder or rolling mill.

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10. What advantage is gained by the use of the _rolling barrels_?

It lessens the duration and danger of pounding in the mortars. After the ingredients are pulverized and mixed in the rolling barrels, the mixture is placed under the pestles of the _pounding mill_, 10 per cent. of water is added, and it is beaten for three hours only.

11. Which mill is now generally used?

The CYLINDER MILL, which forms 50 lbs. of composition into cake in from one to three hours.

12. Does powder inflame instantaneously?

No; its inflammation is gradual, and progressive, and in a gun the projectile commences to move before the whole charge is ignited.

13. Why should gunpowder be grained?

In order to facilitate the transmission of the flame. When the powder is very fine, and in large and compact charges, the flame cannot penetrate it, and it burns slowly and in successive layers.

14. Which burns quickest, the small or large grained powder?

Before coming to the limit of dust, the smaller the grain, the more rapid the combustion, and the greater the bursting force of the powder.

15. What is the difference between the ignition and combustion of large and small grained powder?

With the large grained, the ignition is more rapid, but the combustion slower; with small grains, the contrary is the case.

16. Why should the grains be angular?

Because they present a greater surface to the action of the flame, and therefore burn quicker.

17. Why should powder be free from dust?

Because the dust fills up the intervals between the grains, and forming a compact mass, retards combustion.

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18. To what special purpose are large and small grained powders applied?

The large for cannon, and the small for small arms.

19. How is the size of the grain for each kind of powder tested?

By means of sieves or gauges.

20. How many grains of powder are in 10 grs. Troy weight?

_Cannon_, 150; _Musket_, 2,000 to 2,500; and _Rifle_, 12,000 to 15,000.

21. What is the object in glazing powder?

Glazed powder does not absorb moisture, or break up in transportation, so much as unglazed.

22. What is the established mode of proving the strength of powder in the U. S.?

A sample is taken from each barrel, and the strength determined by the eprouvette mortar.

23. What is the least range allowed?

The general _mean-range_ of new powder must not be less than 250 yards; but no powder ranging below 225 yards is received.

24. When is powder in magazines considered unserviceable.

When it does not range over 180 yards.

25. What is the range of good powder?

Cannon from 280 to 300 yards. Small grained from 300 to 320 yards.

26. What other means is there for determining the strength of powder?

The GUN AND BALLISTIC PENDULUM, and NAVEZ’ ELECTRO-BALLISTIC MACHINE. The latter is considered the best for determining the initial velocity.

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27. What is the hygrometric proof of powder?

Samples are placed in shallow tin pans, set in a tub, the bottom of which is covered with water; the pans should be about an inch above the water, and the tub covered. Good powder will not absorb more than 2½ per cent. in 24 hours.

28. How can the relative quickness of two kinds of powder be determined?

By burning a train laid in a circular or other groove, which returns into itself, made in a piece of hard wood: one-half of the groove being filled with each kind of powder, and fire communicated at the junction of the two trains, the relative quickness is readily deduced from observation of the point at which the flames meet.

29. What are the qualities of good powder?

It should be perfectly free from dust, uniform in strength and size of grains, angular and irregular in form; in color, brownish black, or slate color; so hard as not to be easily crushed by pressure with the finger; and should leave no beads or foulness when flashed in quantities of 10 grs. on a copper plate.

30. What is the expansive velocity, and pressure of ignited powder?

The expansive velocity is about 5,000 feet per second, and pressure about 2,000 atmospheres.

31. What is the weight of a cubic inch of powder?

About half an ounce; a cubic foot will therefore weigh about 54 pounds, and 32 cubic inches, one pound.

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32. How is government powder packed?

In barrels of 100 lbs. each; the barrels being large enough to allow sufficient space for the powder to move when rolled to prevent its caking.

33. How are the barrels marked?

On one head with the _place_ and _year_ of manufacture, and with the kind of grain, _cannon_, _musket_ or _rifle_; on the other head with the _year_ in which it was _proved_ and the _proof-range_, leaving room for subsequent proofs, which are marked in the same manner.

34. When powder is injured by dampness, can it be restored?

If the water absorbed does not exceed 7 per cent., it can be by drying. If it has absorbed from 7 to 12 per cent., after drying, it remains porous and friable, and is unfit for transportation. In this case it is better to work it over.

35. How is powder stored?

In magazines especially constructed for the purpose. The barrels are generally placed near the sides, three tiers high, or four tiers if necessary; small skids should be placed on the floor and between the several tiers of barrels, in order to steady them, and chocks should be placed at intervals on the lower skid, to prevent the rolling of the barrels.

36. How are the different kinds of powder arranged?

Those barrels of the same kind, place and date of fabrication, and proof range, are piled together.

37. Should it be necessary to pile the barrels more than four tiers high, what is done?

The upper tiers are supported by a frame resting on the floor; or the barrels may be placed on their heads, with boards between the tiers.

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38. What is necessary for the preservation of the powder?

The magazine should be opened and aired in clear dry weather, and the ventilators should be kept free.

39. How may the moisture of a magazine be absorbed?

By chloride of lime suspended in a box under the arch, and renewed from time to time.

40. When the magazine is open, what precautions should be observed?

The sentinel or guard should have no fire-arms, and any one who enters it should take off his shoes, or put socks over them. No sword or cane, or anything which might occasion sparks should be carried in.

41. How should powder in barrels be transported?

The barrels should never be rolled; they should be carried in hand-barrows, or slings made of rope or leather. In wagons, the barrels should be packed in straw, and not allowed to rub against each other, and the whole covered with thick canvas.

42. What precaution should be used to prevent powder caking?

The barrels should be taken outside the magazine and rolled on boards.

43. Where should cartridge bags be filled?

In the filling room of the laboratory, or a small magazine, and not in the general magazine.

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