THE ROYAL ARTILLERY INSTITUTION. 
375 
after the gun cotton has been stored in wooden or metal-lined cases, even if these are kept ventilated. 
These circumstances may prove not to be an indication of any important change in the gun cotton, but, 
at any rate, this is a matter which requires careful watching and the most rigid investigation, and 
which does certainly not admit of being explained away by a reference to possible acid emanations 
from pine-chests in which the gun cotton may have been stored ; or, to the long-continued treatment 
with acids which the cotton has received (one of the leading features of Baron Lenk’s system being 
the most complete purification from acid to which it is afterwards submitted, and by which its 
permanent characters are believed to be secured). 
On the other hand, the possibility hinted at, that certain higher nitro-compounds, of which minute 
quantities may always exist in Lenk’s gun cotton, are more liable to decomposition than the actual 
gun cotton y and that the acid observed may be the result of their change, is entitled to full con¬ 
sideration. Chemists who have paid attention to this subject, have some grounds for believing that, 
among the compounds obtainable by the action of mixed nitric and sulphuric acids upon cotton wool, 
the tri-nitro cellulose (i.e. gun cotton as obtained by Lenk’s system), possesses the greatest 
stability]. 
Spontaneous Decomposition of Gunpowder . 
9. These acid traces should the less evoke surprise, when we bear in 
mind that the gun cotton in process of manufacture had been exposed for 
forty-eight hours to a strong acid bath: moreover, if the subject of 
comparison, viz. gunpowder, be tested with equal severity, similar evidence 
of chemical action would be forthcoming. The courses of testing must, 
however, be different. 
Gunpowder contains sulphur, as is well known. Sulphur being an element, 
cannot be decomposed : nevertheless, it is affected by the atmosphere, though 
slowly. 
The change here is oxidation, the product being sulphurous acid. This 
oxidation imperceptibly affects solid cakes or bars of sulphur, but more rapidly 
if the sulphur be powdered. Now, gunpowder contains sulphur in the 
highest degree of comminution, and if gunpowder be smelt, sulphurous acid 
is easily perceived. Other evidence is, however, available. 
The sulphurous acid resulting from decomposition of sulphur is slowly 
changed into sulphuric acid, which latter partly attacks the saltpetre, and 
is partly neutralized by the potash of the ashy parts of the charcoal. 
Gunpowder has a weak alkaline action, although each of the constituents 
of gunpowder is absolutely neutral. The alkalinity can only result from 
potash contained as an impurity in the charcoal. These facts borne in 
mind, it follows that any sulphuric acid (resulting from sulphurous acid), 
developed in gunpowder, should be found united with potash as sulphate 
of potash. Now, the presence of sulphuric acid is easily demonstrable in 
affected gunpowder by the test of chloride of barium; and, inasmuch as 
sulphuric acid does not exist in either of the original constituents, it must 
necessarily be a product of decomposition. 
[The reference here made to minute changes which occur in gunpowder, apparently with the object 
of leading the reader to infer that the acidity, noticed in stored gun cotton, is of no greater importance 
than they are, is certainly calculated to mislead, and might have the effect of diverting the necessary 
attention from a point which demands most minute examination. No chemist would suppose for an 
instant that the minute changes which occur in gunpowder could ever lead to a chemical action 
between its constituents, resulting in the generation of heat sufficient to effect the ignition of the 
powder; but all chemists know that gun cotton belongs to a class of bodies including many exceedingly 
prone to changes, which occur, in some instances, with great energy and rapidity, and are consequently 
[VOL. III.] 
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