ON THE APPLICATION OF GUN-COTTON TO WARLIKE PURPOSES, 23 
in store, of the finished gun-cotton, can hardly be passed over altogether with- 
out notice in this communication, though the precise nature and cause of the 
result which has manifested itself are still undetermined. 
by far the larger proportion of the gun-cotton prepared at Waltham Abbey 
was dried in the open air, being exposed to strong daylight, and very fre- 
quently to powerful sunlight. When dry, it was packed into ammunition- 
boxes—large wooden cases containing an internal casing of tinned copper and 
with very tightly closing double lids. In opening some of these boxes con- 
taining gun-cotton, a faint but peculiar odour was accidentally observed, which 
was more distinct in some boxes than others. This observation led to the 
introduction of some pieces of litmus-paper among the skeins in different 
boxes, and these were found in some instances to change, after the lapse of 
time, to rose-colour, some merely at the edges, others more or less perfectly 
throughout. The change of colour was like that produced by carbonic acid 
upon litmus; and if the boxes were left open for some time, the paper gra- 
dually regained its original colour. If they were again closed for twenty-four 
hours or longer, the reaction upon the litmus-paper was again observed in 
those instances in which it had first been decidedly manifest, but it has been 
noticed to become gradually weaker. It was subsequently found that the 
gun-cotton, after it had been for some time exposed to strong daylight, and 
particularly to sunlight, in the open air, exhibited the same slight acidity, and 
that the reaction noticed in the boxes was always more marked in those which 
contained the gun-cotton most recently exposed for drying. 
As above stated, no satisfactory explanation can as yet be afforded of the 
occasional exhibition of this slight acidity in the thoroughly purified gun- 
cotton under the circumstances described ; to whatever causes it may be due, 
it appears evident, on a perusal of the report of Drs. Redtenbacher, Schrotter, 
and Schneider upon Baron Lenk’s gun-cotton, that those chemists have no- 
ticed a similar occasional acidity as occurring in the Hirtenberg cotton, and, 
indeed, that this acidity has been dwelt upon as a cause for alarm by persons 
who have feared the spontaneous decomposition of the gun-cotton. The sur- 
mises as to its possible origin, put forward in the report above referred to, are, 
it must be confessed, not very satisfactory ; neither, in the face of the extra- 
ordinary precautions adopted for effecting the complete purification of the 
gun-cotton, is the force of the following concluding paragraph of that part of 
the report which refers to this subject, very apparent :—“ 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 will be forthcoming.” It is 
in a material in which, in the first instance, the most delicate tests fail to de- 
tect the slightest evidence of free acid, that this slight acidity occasionally be- 
comes evident. That exposure to light will, after some time, induce decom- 
position in the most carefully purified gun-cotton, is beyond dispute: as the 
latest of many proofs, which I myself have had of this, I may mention that 
some litmus-paper which has been for a few weeks exposed to light in a stop- 
pered glass bottle, together with a piece of the Hirtenberg cotton, has become 
already perfectly bleached. But that an indication of change, such as has 
been dwelt upon above, should be afforded by so brief an exposure to light as 
five or six hours, and continue to be afforded after the cotton has been removed 
from light, appears to me to favour one of the conjectures put forward in the 
report referred to,—namely, that the gun-cotton may contain traces of high 
nitro-compounds which are much more liable to decomposition than it is itself 
