1864. ] Russriy on Gun-cotton. 403 
being the condensed steam which forms one of the products of its 
decomposition. Gun-cotton is, therefore, superior to gunpowder in 
not fouling the gun, a result favourable both to quicker and more 
accurate firing. 
It is further a matter of no slight convenience that gun-cotton 
makes no smoke. In mines the smoke of gunpowder makes the air 
unbreathable, and for some time after explosion the miners cannot 
return to their work. In boring the great tunnel of Mont Cenis 
through the Alps, the delay from smoke of powder alone will postpone 
the opening of the line for many months. After a properly-conducted 
explosion of gun-cotton, the workmen may proceed in their work at 
once without inconvenience. 
In casemates of fortresses, gunpowder fills the casemates with foul 
smoke, and the men speedily sink under the exertion of quick firing. 
By using gun-cotton it was ascertained that the men could continue 
their work unharmed for double the quantity of firing. This is partly 
attributed to the greater heat, and partly to the foulness of the air 
produced by gunpowder. 
But it is under the decks of our men-of-war, that greatest benefit 
is likely to arise from gun-cotton. Not only does the smoke of a 
broadside fill the between decks with hot and foul air, but the smoke 
of the windward gun blinds the sight, and hinders the aim of the lee- 
ward. When there is no smoke, as with gun-cotton, the aim of every 
gun may be precise and deliberate. The diminished heat between 
decks will also tell powerfully in favour of gun-cotton. In our 
armour-plated ships also there is more value in breech-loading guns, 
than in any other use of artillery. It is one of the necessities of 
breech-loading mechanism, that it be kept clean, and nothing tends 
more to derange its perfect action than the greater heat which gun- 
powder imparts to the gun from which it is fired. 
That gun-cotton has the convenience of not heating the gun has 
been thus proved. 100 rounds were fired in 34 minutes with gun- 
cotton, and the temperature of the gun was raised 90°. 100 rounds 
were fired with gunpowder, and triple the time allowed to cool the 
gun, which nevertheless was heated so much as to evaporate water with 
a hissing sound, which indicated that its temperature was much above 
212°. Under these circumstances the firmg with gunpowder had to be 
stopped, while that with gun-cotton was comfortably continued to 180 
rounds. 
It is also a matter of practical convenience that gun-cotton, inso- 
much as it is lighter, can be carried more easily and farther than gun- 
powder ; and it may be wetted without danger, so that when dried 
again in the open air, it is as good for use as before. 
III. We have now to ask—is it cheaper? The answer to this 
question must be qualified—pound for pound it is dearer; we must 
therefore judge of its cheapness by its effect, not by weight merely. 
But where it does six times as much work, it can then be used at six 
times the price per pound and still be as cheap as gunpowder. As far 
as we yet know, the prices of gun-cotton and gunpowder are nearly 
equal, and it is only therefore where the one has advantages and con- 
