Powders in the five following proportions were prepared:—
| Nitre. | Charcoal. | Sulphur. | |||||
|---|---|---|---|---|---|---|---|
| 1 | 76 | 14 | 10 | Gunpowder of Bâle. | |||
| 2 | 76 | 12 | 12 | Gunpowder works of Grenelle. | |||
| 3 | 76 | 15 | 9 | M. Guyton de Morveau. | |||
| 4 | 77 | ·32 | 13 | ·44 | 9 | ·24 | Idem. |
| 5 | 77 | ·5 | 15 | 7 | ·5 | M. Riffault. | |
The result of more than two hundred discharges with the proof-mortar shewed that the first and third gunpowders were the strongest; and the commissioners in consequence recommended the adoption of the third proportions. But a few years thereafter it was thought proper to substitute the first set of proportions, which had been found equal in force to the other, as they would have a better keeping quality, from containing a little more sulphur and less charcoal. More recently still, so strongly impressed have the French government been with the high value of durability in gunpowders, that they have returned to their ancient dosage of 75 nitre, 121⁄2 charcoal, and 121⁄2 sulphur. In this mixture, the proportion of the substance powerfully absorbent of moisture, viz. the charcoal, is still further reduced, and replaced by the sulphur, or the conservative ingredient.
If we inquire how the maximum gaseous volume is to be produced from the chemical reaction of the elements of nitre on charcoal and sulphur, we shall find it to be by the generation of carbonic oxide and sulphurous acid, with the disengagement of nitrogen. This will lead us to the following proportions of these constituents:—
| Hydrogen = 1. | Per cent. | |||
|---|---|---|---|---|
| 1 | prime equivalent of | nitre | 102 | 75·00 |
| 1 | ... | sulphur | 16 | 11·77 |
| 3 | ... | charcoal | 18 | 13·23 |
| 136 | 100·00 | |||
The nitre contains five primes of oxygen, of which three, combining with the three of charcoal, will furnish three of carbonic oxide gas, while the remaining two will convert the one prime of sulphur into sulphurous acid gas. The single prime of nitrogen is, therefore, in this view, disengaged alone.
The gaseous volume, on this supposition, evolved from 136 grains of gunpowder, equivalent in bulk to 751⁄2 grains of water, or to three-tenths of a cubic inch, will be, at the atmospheric temperature, as follows:—
| Grains. | Cubic Inches. | ||
|---|---|---|---|
| Carbonic oxide | 42 | = | 141·6 |
| Sulphurous acid | 32 | = | 47·2 |
| Nitrogen | 14 | = | 47·4 |
| 236·2 | |||
being an expansion of one volume into 787·3. But as the temperature of the gases at the instant of their combustive formation must be incandescent, this volume may be safely estimated at three times the above amount, or considerably upwards of two thousand times the bulk of the explosive solid.