368 
MINUTES OF PROCEEDINGS OF 
It is true that gun cotton has frequently and by various persons been 
manufactured by modifications of one of the two following processes* 
viz.:— 
(1) By acting on cotton with mixtures of nitric and sulphuric acid. 
(2) By acting on cotton with mixtures of saltpetre and sulphuric acid. 
These two general processes have been so much varied in detail by 
different experiments* that the resulting specimens of gun cotton must 
necessarily have been most diverse in quality. The variations of detail may 
be classified as follows* viz :— 
(1) Yariations as to strength of acids. 
(2) Yariations as to the conditions of mingling the acids. 
(3) Yariations as to duration of chemical action. 
(4) Yariations as to temperature. 
(5) Yariations as to the removal of free acid from the resulting gun 
cotton. 
These variable conditions being taken into consideration* it is no longer 
a matter of surprise that even the chemical composition of gun cotton has 
been differently stated by different authorities. Accordingly, whilst one 
set of chemists* in explaining the rationale of action whereby ordinary cotton 
is changed into gun cotton* refer the change to a substitution of one 
equivalent of hyponitric acid for three equivalents of hydrogen in the 
original cotton* another set affirm that four equivalents represent the 
hydrogen exchanged; and yet other chemists* five equivalents. In addition 
to these three definite compounds* various analyses have testified to an 
infinity of secondary bodies* the result of mechanical mixtures. 
Unforeseen explosions of gun cotton occurring without any known cause* 
and assumed to have been the result either of spontaneous combustion* 
or of some unimportant elevation of temperature* as up to 50° or 60° C.* have 
frequently been chronicled in the short history of this substance; whilst* 
on the other hand* reliable authorities have fixed the exploding temperature 
between 130° and 160° C.—another proof as to the variety of materials 
operated upon on a small scale. The chief experiments relative to gun 
cotton have been made by chemists upon small portions* one pound being 
looked upon as a considerable quantity. Results based on such data may 
be considered on a par with general conclusions as to the properties of 
gunpowder founded upon experiments with a mixture by hand of charcoal* 
sulphur* and nitre* in quantities yielding a pound weight aggregate. 
Chemical changes involved in the manufacture of Cun Cotton . 
2. The fact should be borne in mind* that the changes which cotton 
undergoes in its treatment with nitric and sulphuric acids conjointly* are 
not alone peculiar to cotton and other vegetable fibre* but that a great 
number of organic bodies are amenable to a corresponding change if- 
they be similarly treated. The exact grade of mutation which any particular 
