75 parts of nitre, specific gravity = 2·000
15 parts of charcoal, specific gr. = 1·154
10 parts of sulphur, specific gr. = 2·000
The volume of these constituents is 55·5, (the volume of their weight of
water being 100;) by which if their weight 100 be divided, the quotient
is 1·80.
The specific gravity of the first and second of the above powders,
including the interstices of their grains, after being well shaken down
in a phial, is 1·02. This is a curious result, as the size of the grains
is extremely different. That of Pigou and Wilks similarly tried is only
0·99; that of the Battle powder is 1·03; and that of Curtis and Harvey
is nearly 1·05. Gunpowders thus appear to have nearly the same weight as
water, under an equal bulk; so that an imperial gallon will hold from 10
pounds to 10 pounds and a half, as above shown.
The quantities of water which 100 grains of each part with on a steam
bath, and absorb when placed for 24 hours under a moistened receiver
standing in water, are as follows:
100 grains
of Waltham Abbey, lose 1·1 by steam heat, gain 0·8 over water.
of Hall 0·5 2·2
Lawrence 1·0 1·1
Pigou and Wilks 0·6 2·2
Curtis and Harvey 0·9 1·7
Thus we perceive that the large-grained government powder resists the
hygrometric influence better than the others; among which, however,
Lawrence’s ranks nearly as high. These two are therefore relatively the
best keeping gunpowders of the series.
The process most commonly practised in the analysis of gunpowder seems
to be tolerably exact. The nitre is first separated by hot distilled
water, evaporated and weighed. A minute loss of salt may be counted on,
from its known volatility with boiling water. I have evaporated always
on a steam bath. It is probable that a small portion of the lighter and
looser constituent of gunpowder, the carbon, flies off in the operations
of corning and dusting. Hence, analysis may show a small deficit of
charcoal below the synthetic proportions originally mixed. The residuum
of charcoal and sulphur left on the double filter-paper, being well
dried by the heat of ordinary steam, was estimated, as usual, by the
difference of weight of the inner and outer papers. This residuum was
cleared off into a platina capsule with a tooth-brush, and digested in a
dilute solution of potash at a boiling temperature. Three parts of
potash are fully sufficient to dissolve out one of sulphur. When the
above solution is thrown on a filter, and washed first with a very
dilute solution of potash boiling hot, then with boiling water, and
afterwards dried, the carbon will remain; the weight of which deducted
from that of the mixed powder, will show the amount of sulphur.
I have tried many other modes of estimating the sulphur in gunpowder
more directly, but with little satisfaction in the results. When a
platina capsule, containing gunpowder spread on its bottom, is floated
in oil heated to 400° Fahrenheit, a brisk exhalation of sulphur fumes
rises, but, at the end of several hours, the loss does not amount to
more than one half of the sulphur present.
The mixed residuum of charcoal and sulphur digested in hot oil of
turpentine gives up the sulphur readily; but to separate again the last
portions of the oil from the charcoal or sulphur, requires the aid of
alcohol.
When gunpowder is digested with chlorate of potash and dilute muriatic
acid, at a moderate heat in a retort, the sulphur is acidified; but this
process is disagreeable and slow, and consumes much chlorate. The
resulting sulphuric acid being tested by nitrate of baryta, indicates of
course the quantity of sulphur in the gunpowder. A curious fact occurred
to me in this experiment. After the sulphur and charcoal of the
gunpowder had been quite acidified, I poured some solution of the baryta
salt into the mixture, but no cloud of sulphate ensued. On evaporating
to dryness, however, and redissolving, the nitrate of baryta became
effective, and enabled me to estimate the sulphuric acid generated;
which was of course 10 for every 4 of the sulphur.
The acidification of the sulphur by nitric or nitro-muriatic acid is
likewise a slow and unpleasant operation.
By digesting gunpowder with potash water, so as to convert its sulphur
into a sulphuret, mixing this with nitre in great excess, drying and
igniting, I had hoped to convert the sulphur readily into sulphuric
acid. But on treating the fused mass with dilute nitric acid, more or
less sulphurous acid was exhaled. This occurred even though chlorate of
potash had been mixed with the nitre to aid the oxygenation.
The following are the results of my analyses, conducted by the first
described method:
+---------------------+------+---------+--------+------------+
|100 grains afford, of|Nitre.|Charcoal.|Sulphur.| Water. |
+---------------------+------+---------+--------+------------+
|Waltham Abbey | 74·5 | 14·4 | 10·0 |1·1 |
|Hall, Dartford | 76·2 | 14·0 | 9·0 |0·5 loss 0·3|
|Pigou and Wilks | 77·4 | 13·5 | 8·5 |0·6 |
|Curtis and Harvey | 76·7 | 12·5 | 9·0 |1·1 loss 0·7|
|Battle Gunpowder | 77·0 | 13·5 | 8·0 |0·8 loss 0·7|
+---------------------+------+---------+--------+------------+
It is probable, for reasons already assigned, that the proportions mixed
by the manufacturers may differ slightly from the above.
The English sporting gunpowders have long been an object of desire and
emulation in France. Their great superiority for fowling pieces over the
product of the French national manufactories, is indisputable. Unwilling
to ascribe this superiority to any genuine cause, M. Vergnaud, captain
of French artillery, in a little work on fulminating powders lately
published, asserts positively, that the English manufacturers of ‘poudre
de chasse’ are guilty of the ‘charlatanisme’ of mixing fulminating
mercury with it. To determine what truth was in this allegation, with
regard at least to the above five celebrated gunpowders, I made the
following experiments:
One grain of fulminating mercury, in crystalline particles, was mixed in
water with 200 grains of the Waltham Abbey gunpowder, and the mixture
was digested over a lamp with a very little muriatic acid. The filtered
liquid gave manifest indications of the corrosive sublimate, into which
fulminating mercury is instantly convertible by muriatic acid; for
copper was quicksilvered by it; potash caused a white cloud in it that
became yellow, and sulphuretted hydrogen gas separated a dirty yellow
white precipitate of bisulphuret of mercury. When the Waltham Abbey
powder was treated alone with dilute muriatic acid, no effect whatever
was produced upon the filtered liquid by the sulphuretted hydrogen gas.
200 grains of each of the above sporting gunpowders were treated
precisely in the same way, but no trace of mercury was obtained by the
severest tests. Since by this process there is no doubt but one 10,000th
part of fulminating mercury could be detected, we may conclude that
Captain Vergnaud’s charge is groundless. The superiority of our sporting
gunpowders is due to the same cause as the superiority of our cotton
fabrics--the care of our manufacturers in selecting the best materials,
and their skill in combining them.