546 Royal Society :— 



tained from Stowmarket ; otlier exceptional products have also been 

 produced by purposely modifying, in several ways, the system of 

 manufacture as pursued at Waltham Abbey. The very consider- 

 able difference exhibited between some of these and the ordinary 

 products in their behaviour under equal conditions of exposure to 

 heat and light, affords good grounds for the belief that the attain- 

 ment of certain exceptional results, upon which the conclusions of 

 Pelouze and Maury's report condemnatory of gun-cotton, have been 

 principally founded, are to be ascribed to such variations in the nature 

 of the material operated upon. 



Very numerous and extensive experiments and observations have 

 been carried on during the last four years at Woolwich, both with 

 small and large quantities of gun-cotton, for the purpose of completely 

 investigating the conditions by which the stability of this substance, 

 when under the influence of light and heat, maybe modified, and 

 with the view of ascertaining whether results recently arrived at in 

 France apply to gun-cotton as manufactured in this country. 



The principal points which have been established by the results 

 arrived at in these investigations may be summed up as follows : — 



1. Gun-cotton produced from properly purified cotton, according 

 to the directions given by Von Lenk, may be exposed to diffused day- 

 light, either in the open air or in closed vessels, for very long periods 

 without undergoing any change. The preservation of the material 

 for 3^- years under those conditions has been perfect. 



2. Long-continued exposure of the substance in a condition of 

 ordinary dryness to strong daylight and sunlight produces a very 

 gradual change in gun-cotton of the description defined above ; and 

 therefore the statements which have been published regarding the 

 very rapid decomposition of gun-cotton when exposed to the sun- 

 light do not apply to the nearly pure trinitrocellulose obtained by 

 strictly following the system of manufacture now adopted. 



3. If gun-cotton in closed vessels is left for protracted periods 

 exposed to strong daylight or sunlight in a damp or moist condition, 

 it is affected to a somewhat greater extent ; but even under these 

 circumstances the change produced in the gun-cotton by several 

 months' exposure is of a very trifling nature. 



4. Gun-cotton which is exposed to sunlight until a faint acid 

 reaction has become developed, and is then immediately afterwards 

 packed into boxes which are tightly closed, does not undergo any 

 change during subsequent storage for long periods. (The present 

 experience on this head extends over 3 j years.) 



5. Gun-cotton prepared and purified according to the prescribed 

 system, and stored in the ordinary dry condition, does not furnish any 

 indication of alteration, beyond the development, shortly after it is first 

 packed, of a slight peculiar odour and the power of gradually impart- 

 ing to litmus, when packed with it, a pinkish tinge. 



6. The influence exercised upon the stability of gun-cotton of 

 average quality, as obtained by strict adherence to Von Lenk's system 

 of manufacture, by prolonged exposure to temperatures considerably 

 exceeding those which are experienced in tropical climates is very 



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