ME. ABEL’S EESEAECHES ON GEN-COTTON. 
199 • 
100° C. in conical assay flasks, into which long quill-tubes were fitted. The following 
results were observed. 
Table II. 
Number of 
experiment 
Nature of 
gun-cotton. 
Nitrous vapours 
first observed after 
commencement of 
experiment. 
Other observations. 
32 
Coarse yam from 
In 5 hours, very 
The gun-cotton was heated 5 hours daily for 6 days. The nitrous fumes were 
W altham Abbey, 
made in 1863. 
faint colour. 
never more than very faint, and were no longer visible after the close of the 
third day’s experiment. At the close of the 6th day the gun-cotton had 
scarcely altered in appearance. The specimen was destroyed on the 7th day 
by the explosion of a neighbouring vessel. 
33 
Fine yarn from 
Waltham, made 
in 1864. 
In 2 hours, faint ) 
colour. 
1 
The atmosphere in the flasks was deeply coloured at the expiration of the 6th 
34 
Fine yarn from 
Waltham, made 
in 1 866. 
In 2 hours. ( 
1 
) 
hour ; the experiments were therefore interrupted. 
35 
Medium sized yarn, 
In I-) hour, very 
The atmosphere in the flask became deeply coloured after 5 hours’ exposure 
to 100° C. 
Waltham, 1864. 
faint colour. 
36 
Coarse yarn made 
at Waltham, 
1864. 
In 30 minutes. 
The vessel was filled with deep-coloured vapours after 5 hours’ exposure. 
The experiment was continued on the next day, when, after further exposure 
to 100 J C. for 4 hours, the specimen exploded. 
37 
Stowmarket, coarse 
yarn, 1 864 (early 
manufacture). 
In 10 minutes. 
Nitrous vapours were abundantly evolved within 10 minutes, and continued 
to increase until the experiment was arrested. 
38 
Stowmarket, coarse 
None observed du- 
After 9 days’ exposure no nitrous vapours were observed in the vessel. The 
yarn (another 
ring 9 days’ ex- 
specimen had an acid reaction and somewhat pungent odour, but was not 
specimen). 
posure, 5 hours 
daily. 
otherwise altered. 
39 
A portion of the 
same sample as38. 
Very faint after 15 
hours’ treatment. 
The nitrous vapours became more evident on the 4th day of the experiment. 
These eight experiments, conducted precisely alike, point to very important differ- 
ences in the powers of different specimens of gun-cotton to resist destruction by expo- 
sure to 100° C. Of five samples manufactured at Waltham Abbey, only one exhibited 
the effects of such exposure described by Pelouze and Maury as invariable, namely, the 
disengagement of nitrous vapours within a few minutes. One specimen did not exhibit 
this sign of change until after five hours’ exposure, and then only to a very slight extent. 
Of two specimens of gun-cotton from Stowmarket, one decomposed with very consider 
able rapidity at 100° C., and the other did not, in one experiment, evolve any visible 
amount of nitrous acid during forty-five hours’ exposure, in nine days, and exhibited 
very slight signs of change at the expiration of this severe treatment ; while in a second 
experiment, with a portion of the same sample, slight decomposition became apparent 
at the close of the third day’s exposure of five hours. 
The cause of the latter difference in the behaviour of one and the same sample, upon 
different occasions, was traced to the circumstance that the specimen, in the condition 
in which it was first employed, contained a somewhat larger proportion of moisture 
than when the experiment was repeated with it, in consequence of its having been in a 
damp locality for a short time before the first portion was operated upon. Thus one 
possible reason for the different behaviour of several samples of gun-cotton prepared 
by one and the same process was indicated. In confirmation of the influence exerted 
by moisture in retarding the decomposition of gun-cotton exposed to a high tempera- 
ture, the results of a preliminary experiment may be here recorded, which was insti- 
tuted with a sample of gun-cotton found to be very readily affected by exposure to heat. 
2 e 2 
