ME. ABEL’S EESEAECHES OK GUN-COTTON, 
195 
138°-5 C. Schrotter, Redtenbacher, and Schneider, in their report upon Yon Lenk’s 
gun-cotton, mention that 136° C. is the lowest temperature fixed by VonEBNER at which 
this material explodes. 
EFFECTS UPON GUN-COTTON OE EXPOSURE TO 100° C. 
Pelouze and Maury, in their accounts of the effects of heat upon gun-cotton, describe 
several kinds or stages of decomposition as occurring, or producible at will, by its exposure 
to a temperature of 100° C., and state that in every instance they found a few minutes’ 
exposure to that temperature sufficient to produce a disengagement of nitrous vapours. 
A large number of experiments has been instituted with gun-cotton prepared at 
Waltham Abbey and Stowmarket according to Yon Lenk’s direction, and also with some 
specimens of Austrian gun-cotton, with the view of ascertaining the effect upon them of 
exposure to 100° C. The gun-cotton was exposed to heat in sealed tubes and in open 
vessels arranged in different ways. The quantities operated upon and other conditions 
in the experiments were varied, as will be presently particularized, the objects con- 
templated being, in the first instance, to examine into the effects of exposure of gun- 
cotton to heat, and, afterwards, to ascertain if possible by what circumstances those 
effects might be subject to modification. 
The following is a condensed account of the observations made. 
I. j Experiments in sealed tubes . — Experiment 20. Air-dry gun-cotton (coarse yarn, ma- 
nufactured in 1863), enclosed in a stout glass tube hermetically sealed, was maintained 
at 100° C. in a water-bath. The tube was filled with deep orange vapours in about 
three hours. The vapours gradually diminished in intensity, after a time, until the 
gun-cotton was converted into a gum-like mass, the transformation occurring most 
rapidly at the upper end of the tube, where the water produced during the change con- 
densed and returned, charged with acid, upon the gun-cotton. When the sealed tube 
was opened, after continuation of the heat for three or four days (seven hours daily), 
nitric oxide escaped under considerable pressure. Upon -closing the tube again, after 
the escape of gas, and continuing the application of heat, the gun-cotton was gradually 
converted into a black pitch-like mass. 
This experiment, several times repeated, always furnished closely similar results. 
Experiment 21. — A tube containing fine gun-cotton thread, manufactured in 1863, was 
exhausted and sealed. After four hours’ exposure to 100° C., it exploded with great 
violence, tearing open the stout copper water-bath in which it was heated. Portions of 
unburned gun-cotton were scattered about. 
Experiment 22. — Another tube, containing some of the same gun-cotton, was opened 
after seven hours’ heating, to allow the gas to escape, and again sealed. On the second 
day, after heating for three or four hours, it exploded violently. 
Experiment 23. — Several experiments were made with perfectly dry gun-cotton, and 
furnished results quite similar to those obtained with the air-dry material. 
Experiment 24. — Fine gun-cotton thread was introduced into a tube sealed at one 
