ME. ABEL’S EESEAECHES ON GUN-COTTON. 
223 
water (whereby the larger proportion of earthy carbonates attached to the fibre was 
removed) and exposed to heat in comparison with corresponding specimens not thus 
treated. Some other samples were extracted with dilute acid and washed ; but as acetic 
acid was used in most of those experiments, the results of their exposure to heat (expe- 
riments 90-93) were not of the nature anticipated, for the reason, as already explained, 
that the treatment in question removed not merely carbonates but also a proportion of 
the organic impurities. The extraction of the gun-cotton with dilute hydrochloric acid 
does not remove organic impurities ; and, as has already been shown, this treatment has 
the effect of rendering ordinary gun-cotton more susceptible to the destructive effects of 
high temperatures. 
A considerable quantity of Waltham gun-cotton, after having been purified in the 
usual way, was saturated with a solution of sodic carbonate of sufficient strength to 
deposit from 04 to 05 per cent, of the salt in the gun-cotton, after the latter had been 
expressed in the hydro-extractor and dried.' Portions of the material thus prepared were 
carefully washed out in distilled water and submitted to heat in comparison with corre- 
sponding samples of the “ alkalized ” gun-cotton. The washing process did not merely 
extract the sodic carbonate, it also effected the mechanical removal of a large proportion 
of the earthy carbonates deposited upon the gun-cotton during the long-continued washing 
in spring- or river-water. 
The results observed in this series of experiments are given in the two following 
Tables. 
Table VII. 
Description of 
gun-cotton. 
Quan- 
tity 
em- 
ployed. 
Total expo- 
sure to 100° C. 
Interval be- 
tween first ex- 
posure and 
first signs of 
decom- 
position. 
grms. 
Tine yarn, Wal- 
22 
11 hours in 
7 hours 
tham, impreg- 
3 days (14 
nated with 0-4 
hour on the 
per cent, of sodic 
3rd day). 
carbonate. 
The same descrip- 
22 
164 hours in 
8 hours 
tion as used in 
3 days (24 
experiment 122. 
hours on 
3rd day). 
Loss of weight 
sustained by 
the 
gun-cotton. 
Temperature observations. 
Other observations. 
2 - 6 per cent 
in 14 hours 
(2 days). 
During 4-J hours’ heating on the 1st 
day no indications of a rise of 
temperature were obtained. Aftei 
2 hours’ heating on the 2nd day, 
the temperature rose very slowly, 
reaching 106° C. by the close of 
the day’s experiment ; an interval 
of 1 day elapsed before the expe- 
riment was resumed. Upon ex- 
posure to heat on the 3rd day. 
the temperature speedily exceed- 
ed 1 00° ; in 1 4 hour, it had reach- 
ed 113° C., and soon afterwards 
the gun-cotton exploded. 
At the close of the 1st day (after 
64 hours) the temperature rose 
slowly to 102° C. ; on the 2nd 
day it rose gradually to the same 
temperature and remained sta- 
tionary during 6 hours. On the 
3rd day itrose gradually to 104°-5, 
and remained stationary for 1 4 
hour ; the thermometer then rose 
somewhat rapidly to 1 13° C., and 
the gun-cotton exploded almost 
immediately afterwards. 
The coloration of the atmosphere 
in the vessel was only very faint 
until after 3 hours’ treatment on 
the 2nd day, and the decomposi- 
tion was very gradual when com- 
pared with that in experiments 
made with corresponding quan- 
tities of ordinary gun-cotton. 
The coloration of the atmosphere 
in the flask was very faint on the 
first day, and there was only a 
slight increase in colour until the 
thermometer passed 104° C. on 
the 3rd day. 
