1864, | Russet on Gun-cotton. 407 
for warlike purposes, which were from time to time received by our 
government, led to experiments on a considerable scale in this country. 
The manufacture of this agent is now in full operation both at the 
Government Powder Works at Waltham Abbey, and also at a large pri- 
vate manufactory at Stowmarket. 
The great danger in the case of the early gun-cotton was its liability 
to spontaneous explosion, and whilst there remained the slightest sus- 
picion of such a possibility, its employment for war purposes was out 
of the question. The investigations of General Lenk have shown 
that this accident is due to imperfect preparation, and that by adopting 
the precautions which he has pointed out, its spontaneous ignition is 
impossible. It has been very clearly established that the lower nitro- 
compounds of cellulose, that is, cotton in which only one or two of 
the atoms of hydrogen are replaced by hyponitric acid, are much more 
easily decomposed than the compound in which the replacement has 
proceeded to its fullest extent. Tri-nitro-cellulose, or true gun-cotton, 
is a remarkably stable compound under all possible atmospheric con- 
ditions, but it is by no means easy to ensure the complete conversion of 
cotton into this body, and it has been shown to be in the highest 
degree probable that the explosions which put a stop to the early 
attempts at utilizing gun-cotton were due to its incomplete conversion. 
The directions given by Schénbein, although successful on the small 
scale, fail when tried with large quantities, and to General Lenk is 
due the credit of devising a process of manufacture which gives an 
absolutely uniform and true chemical compound when working on 
the largest scale. Ordinary gun-cotton is generally made by saturating 
cotton-wool with a mixture of one part of concentrated nitric acid and 
three parts of oil of vitriol, and allowing the mixture to stand at rest 
for one hour; it is then thoroughly washed and allowed to dry in the 
air. This process is tolerably successful when only about half-an- 
ounce of cotton is treated at one time, but it is found to be ineffectual 
in making a uniform and safe material for war purposes. The most 
important of the precautions recommended by General Lenk, are, the 
cleansing and perfect desiccation of the cotton as a preliminary to 
its immersion in the acids; the employment of the strongest acids 
obtainable in commerce ; the steeping of the cotton in a strong mix- 
ture of acids after its first immersion and its partial conversion into gun- 
cotton ; the continuance of the steeping for forty-eight hours ; and the 
thorough purification of the gun-cotton so produced from every trace 
of free acid : this is secured by its being washed in a stream of water 
for several weeks. Subsequently a weak solution of potash may be 
used, but this is not essential. The prolonged continuance of these 
processes, which would appear superfluous at first sight, is really 
essential, when we consider that each cotton fibre is a long, narrow, 
tube, often twisted and even doubled up, and the acid has first to 
penetrate into the very farthest depths of these tubes, and has after- 
wards to be soaked out of them. Hence the necessity of time. 
It appears that gun-cotton, prepared in this manner, is a true 
chemical compound, and is not liable to the objections which have 
been urged against that mixture of compounds which has been usually 
