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MINUTES OF PROCEEDINGS OF 
permanence is not to be fully relied on. Close attention will be directed to 
these points; it may be found that the re-action has no practical importance, 
or, if it has, that means may be devised to guard against its occurrence. 
It is certain that many specimens of gun-cotton which were made some 
years ago have been proved and analyzed without any trace of alteration 
being discovered. 
The effects of heat and damp are the next to be considered. In the action 
of heat gun-cotton certainly lies under a disadvantage as compared with 
gunpowder, for it will explode at a temperature of 277°, whereas gunpowder 
does not explode until the temperature has reached 600°. The fact is 
however said to be unimportant, because, practically, the temperature would 
never be so high as 277° unless it were raised by means which would make 
the gunpowder equally liable to explode. This plea seems satisfactory, pro¬ 
vided only that high degrees of heat, such as may often be experienced 
in hot climates, do not have any injurious effect. 
Gun-cotton can be exploded by percussion if it is placed between iron and 
iron, but only that part which is actually struck takes fire, the rest remains 
unignited. If the cotton is placed on a soft metal, such as copper, or on a 
stone, and is then struck with a hammer, no detonation takes place. 
The facts in connexion with damp are curious. In the first place gun¬ 
cotton, after being thoroughly dried, will absorb and hold twice as much 
moisture as gunpowder does under ordinary circumstances; the usual pro¬ 
portion being 2 per cent, in the former and only 1 per cent, in the latter. 
But having absorbed this quantity (which is immaterial) gun-cotton has no 
tendency to absorb more; it can only be forced to hold as much as 6 or 8 
per cent, of moisture by being exposed in the very dampest situations, and 
it has so little power of retaining this additional quantity that it quickly 
returns to its normal condition when it is put in a drier place. It may even 
be buried in the earth or soaked in water without receiving permanent hurt, 
and requires nothing more than exposure to the open air to restore its 
original condition. 
This property not only affords the means of guarding against explosions 
without hurting the material, but gives great advantages in storage con¬ 
veyance and practical application. To gunpowder damp is ruinous. If 
packed in barrels, and exposed to damp, the portion near the outside forms 
into a cake which gives protection to the rest, but otherwise it will absorb 
moisture until it is actually dissolved, and if once wetted it can only be 
restored to serviceable order by submitting it to nearly the whole process of 
its original manufacture. 
Baron von Lenk states that some gun-cotton, exposed in a room completely 
saturated with moisture, contained only 8 per cent, after remaining there 
thirty-three days: gunpowder under the same conditions absorbed 79’9 per 
cent, in the same time, and was converted in the course of a few weeks into 
a concentrated solution of saltpetre; the gun-cotton remained during the 
latter part of the time in the same state of saturation as it was at the end of 
the first period. The best proof however of its freedom from damage by 
damp alone is that some specimens of a lot of gun-cotton which had been 
buried in the ground in 1847 were dug up in 1863, and showed on careful 
examination no evidence of having undergone the least change. 
