+-+------+---------+-----------------------------------+
| |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, 12-1/2 charcoal, and 12-1/2 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 75-1/2 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.
But this theoretical account of the gases developed does not well accord
with the experimental products usually assigned, though these are
probably not altogether exact. Much carbonic acid is said to be
disengaged, a large quantity of nitrogen, a little oxide of carbon,
_steam of water_, with _carburetted and sulphuretted hydrogen_. From
experiments to be presently detailed, I am convinced that the amount of
these latter products printed in italics must be very inconsiderable
indeed, and unworthy of ranking in the calculation; for, in fact, fresh
gunpowder does not contain above one per cent. of water, and can
therefore yield little hydrogenated matter. Nor is the hydrogen in the
carbon of any consequence.
It is obvious that the more sulphur is present, the more of the dense
sulphurous acid will be generated, and the less forcibly explosive will
be the gunpowder. This is sufficiently confirmed by the trials at
Essonne, where the gunpowder that contained 12 of sulphur and 12 of
charcoal in 100 parts, did not throw the proof-shell so far as that
which contained only 9 of sulphur and 15 of charcoal. The conservative
property is, however, so capital, especially for the supply of our
remote colonies and for humid climates, that it justifies a slight
sacrifice of strength, which at any rate may be compensated by a small
addition of charge.
_Table of Composition of different Gunpowders._
+----------------------------------+------+---------+--------+
| |Nitre.|Charcoal.|Sulphur.|
| +------+---------+--------+
|Royal Mills at Waltham Abbey | 75 | 15 | 10 |
|France, national establishment | 75 | 12·5 | 12·5 |
|French, for sportsmen | 78 | 12 | 10 |
|French, for mining | 65 | 15 | 20 |
|United States of America | 75 | 12·5 | 12·5 |
|Prussia | 75 | 13·5 | 11·5 |
|Russia | 73·78| 13·59 | 12·63 |
|Austria (_musquet_) | 72 | 17 | 16 |
|Spain | 76·47| 10·78 | 12·75 |
|Sweden | 76 | 15 | 9 |
|Switzerland (a round powder) | 76 | 14 | 10 |
|Chinese | 75 | 14·4 | 9·9 |
|Theoretical proportions (as above)| 75 | 13·23 | 11·77 |
+----------------------------------+------+---------+--------+