THE ROYAL ARTILLERY INSTITUTION. 
373 
Unalterable quality of the Lenk Gun Cotton . 
8. Even if invariability of composition in respect of gun cotton be con¬ 
ceded, tbe allegation ,is made, that if kept for a long time it deteriorates; the 
ground of this dictum being sought in experiments which show the alteration 
of the gun cotton to the extent of 100° with regard to litmus paper, and 
also are assumed to reveal a spontaneously explosive quality. The changes 
in the Hirtenberg gun cotton can only be ascertained direct by comparison 
and analysis with other and different samples of gun cotton made on the 
same day when manufactured, and then by repetition of analysis of the same 
portions of cotton after one, two, three, or more years; these results finally 
compared with the first year's analyses: but there exist no such analyses, 
because they were never made. The opponents of gun cotton themselves 
have therefore omitted the only true proof of a changeable quality. Such 
omissions can, nevertheless, be in some degree remedied. 
In the magazines of gun cotton at the Neustadter Haide, there are stores 
of various years. 
In the laboratory of the University there are samples of Hirtenberg gun 
cotton of three several years which have been examined by the above-named 
artillery officers, and they have been found not to differ materially in their 
composition from tri-nitro cellulose. Eor instance— 
Per 
Centage. 
Tri-nitro 
Cullulose. 
No. 3 
of the year 
1856. 
No. 6, 
year 1860. 
No. 14, 
year 1862. 
1862. 
1 
2 
1 
2 
1 
2 
3 
Carbon .. 
24*3 
24-4 
24*5 
24-6 
24-2 
23-6 
23*9 
24-1 
Hydrogen. 
2-3 
2-7 
2-8 
2*6 
2-7 
2*6 
2-4 
2-4 
If these results are compared with each other, there can be no right to say 
that Hirtenberg gun cotton alters by keeping. They agree so far with 
each other as analyses of the same material usually do. It is to be regretted, 
on this as on many other accounts, that during the last twelve years such 
analyses were not frequently repeated. If the opponents of gun cotton, 
in performing an adverse experiment, heat the substance in a test tube up 
to 1000 C., and holding litmus paper over it, deduce from redness of the 
latter that gun cotton changes after long keeping, they merely prove thereby 
that gun cotton changes at 1000° C. Of an explosive compound, it can only 
be required that it shall not deteriorate within certain limits of temperature: 
a requisition amply fulfilled by Lenk’s gun cotton. 
Some varieties of gun cotton, if inclosed together with litmus paper in a 
tube, often manifest an acid reaction at ordinary temperature. This may 
arise from various causes. There may exist, for example, free acids. These 
acids may be the result of nitrogen partially oxidized, and may result 
from imperfectly worked cotton. This assumption granted, the phenomenon 
is explained, and the cause is easily avoided. 
