of 'preparing and employing Gun-cotton. 547 



Without detailing the known cases of decomposition of gun- 

 cotton at the temperature of the places in which it was preserved, 

 we shall limit ourselves to speaking of decompositions which we 

 have observed in specimens of the manufacture of 1847, which 

 had been washed with special care, either with pure or with 

 alkaline water. 



Of twenty-eight specimens less than a few grammes in weight 

 placed in a small stoppered bottle, sixteen had undergone various 

 alterations, 



We took at random one of the altered specimens for ex- 

 amination. This specimen consisted originally of 6 grammes of 

 gun-cotton which had been washed with potash and left from 

 the 17th of March 1850 (14 years) in a stoppered bottle imper- 

 fectly closed. It had left a residue of 79 per cent., of a deep 

 yellow colour, strongly acid, but without sulphuric acid. This 

 residue dissolved completely in water, and, like grape-sugar, re- 

 duced potassio-tartrate of copper. Its boiling solution emitted 

 a fresh acetous odour, and, remarkably enough, it disengaged 

 ammonia under the action of potass. 



Hence, under ordinary atmospheric conditions, there are in- 

 dubitable instances of spontaneous alterations of gun-cotton, 

 and what is more, of a gun-cotton washed with alkaline water. 



But we have seen that, when warm, gun-cotton decomposes in 

 four different ways, that in certain cases it detonates, and that 

 in others, apparently identical, it is destroyed without inflamma- 

 tion. Why should it not be so with gun-cotton kept at low 

 temperatures ? Why in the case of simple decomposition at 

 ordinary temperatures may not cases of detonation also occur ? 

 The analogy is too evident to oblige us to resort to the supposi- 

 tion of bad washings to explain the explosions of gun-cotton. 



We admit that a badly washed gun-cotton is more exposed to 

 decomposition than a well-prepared gun-cotton. But seeing the 

 facility with which all specimens of gun-cotton, of whatever 

 origin, decompose at 60°, and especially seeing that half the 

 specimens kept by one of us under exceptionally favourable cir- 

 cumstances have decomposed, it is right to conclude that the 

 storing of large quantities of gun-colton offers terrible chances 

 of explosion. 



Can we conclude, with General von Lenk, that explosions are 

 impossible, or at any rate very improbable, because he kept for 

 a dozen years without alteration large quantities of gun-cotton ? 

 To do so we must neglect the explosion in Austria, near Sim- 

 mering, which, as we have already said, could only be explained 

 by a spontaneous inflammation of gun-cotton. 



The best- washed gun-cotton, that of General von Lenk, be- 

 comes acid by lengthened exposure to the sun. A gun-cotton 

 originally alkaline, exposed thus to the action of the light for a 



