546 MM. Pelouze and Maurey on the New Methods 



the lapse of some days the flask was seen to fill with thick red 

 vapours ; and the same pulverulent, non-nitrogcnized residue of 

 which we have spoken was obtained. No ignition was observed 

 in these latter experiments. 



We may also mention a decomposition which one of us ob- 

 served when about a gramme of gun-cotton was placed in a Gay- 

 Lussac's hot-air bath containing oil, the temperature of which 

 was only 47°. The gun-cotton thus decomposed came from a 

 specimen prepared by an immersion of forty-eight hours, and 

 soaked by the Lenk method. The detonation, which was very 

 brisk, was exhibited immediately after the gun- cotton had been 

 placed in contact with the metal. 



This fact recalls another, quoted in an Austrian report — the 

 explosion of a specimen at a temperature of 69°. General 

 von Lenk attributed this explosion to sulphuric and perhaps 

 nitric acid remaining in the gun-cotton. Yet our explosion, 

 observed at a lower temperature, was not caused by the presence 

 of these acids. 



We dwell upon this detonation at 47°, because this heat may 

 be attained and even exceeded by the action of the solar rays. 



In fact at the Bouchet powder-mills, that is, in a country 

 with a mean climate, a temperature of 69° was observed in 

 masses of cotton placed in the sun On drying-cloths. 



The preceding experiments show incontestably that, contrary 

 to General von Lenk's assertion, his gun-cotton resists the action 

 of heat no better than the Bouchet. In all these cases the sili- 

 cated Austrian gun-cotton behaved in the same manner as ours. 

 With these facts, of decomposition produced at temperatures 

 near 50°, it may be asked if gun-cotton does not decompose 

 even at ordinary temperatures. Is it susceptible therefore of 

 detonating spontaneously when kept in considerable masses in 

 magazines ? 



Many chemists have quoted examples of the decomposition of 

 gun-cotton at the ordinary temperature. They have generally 

 noted as products of this decomposition nitrous vapours, highly 

 oxidized substances such as formic, oxalic, and acetic acids, and 

 as residue gummy or saccharine substances. These instances 

 of the alteration of gun-cotton at the ordinary temperature, it 

 has been attempted to ascribe to acids left in the gun-cotton by 

 imperfect washing. 



It is first to be observed that washings are easy with small 

 quantities of substance. Then, as was known from the first, 

 sulphuric acid exerts a destructive action on gun-cotton, and it 

 is evident that great care must have been taken to remove the 

 least traces, and therefore the washings must have been made 

 with the greatest care. 



