548 Royal Society : — 



smoke attending its combustion, and in a slight retardation of its ex- 

 plosion, neither of which could be regarded as results detrimental to 

 the probable value of the material. 



10. Water acts as a most perfect protection to gun-cotton (except 

 when it is exposed for long periods to sunlight), even under ex- 

 tremely severe conditions of exposure to heat. An atmosphere 

 saturated with aqueous vapour suffices to protect it from change at 

 elevated temperatures ; and wet or damp gun-cotton may be exposed 

 for long periods in confined spaces to 100° C. without sustaining any 

 change. 



Actual immersion in water is not necessary for the most perfect 

 preservation of gun-cotton ; the material, if only damp to the touch, 

 sustains not the smallest change, even if closely packed in large quan- 

 tities. The organic impurities which doubtless give rise to the very 

 slight development of acid observed when gun-cotton is closely 

 packed in the dry condition, appear to be equally protected by the 

 water; for damp or wet gun-cotton, which has been preserved for 

 three years, has not exhibited the faintest acidity. If as much water 

 as possible be expelled from wet gun-cotton by the centrifugal ex- 

 tractor, it is obtained in a condition in whienj though only damp to 

 the touch, it is perfectly non-explosive ; the water thus left in the 

 material is sufficient to act as a perfect protection, and conse- 

 quently also to guard against all risk of accident. It is therefore 

 in this condition that all reserved stores of the substance should be 

 preserved, or that it should be transported in large quantities to very 

 distant places. If the proper proportion of sodic carbonate be dis- 

 solved in the water with which the gun-cotton is originally saturated 

 for the purpose of obtaining it in this non-explosive form, the 

 material, whenever it is dried for conversion into cartridges, or. em- 

 ployment in other ways, will contain the alkaline matter required for 

 its safe storage and use in the dry condition in all climates. 



Although some experiments, bearing upon the different branches 

 of inquiry included in this memoir, are still in progress with a 

 view to the attainment of additional knowledge of the conditions 

 which regulate the stability of gun-cotton, it is confidently believed 

 that the results arrived at amply demonstrate that the objections 

 which have been of late revived, especially in France, against the 

 employment of gun-cotton, on the ground of its instability, apply only 

 in a comparatively slight degree to the material produced by strictly 

 pursuing the system of manufacture perfected by Von Lenk — that, as 

 far as they do exist, they have been definitely traced to certain difficul- 

 ties in the manufacture of pure gun-cotton which further experi- 

 mental research may, and most probably will, overcome — but that, 

 in the meantime, these objections are entirely set aside by the adop- 

 tion of two very simple measures, against the employment of which 

 no practical difficulties can be raised, and which there is every reason 

 to believe must secure for this material the perfect confidence of those 

 who desire to avail themselves of the special advantages which it 

 presents as an explosive agent. 



