To prepare gun cotton, make a mixture of three parts sulphuric acid
and one part nitric acid; when this has cooled (for it becomes hot
on mixing), put into it some cotton wool, and let it be stirred
about with a glass rod, then taken out, and all the superfluous acid
strained from it; it is then to be covered up for an hour or so. It
should now be thoroughly washed in cold water, so that all the acid
be removed; to ensure this completely, let it be afterwards washed
in a very weak solution of potash, and then dried by a very gentle
heat, produced by either steam or hot water; when dry, soak it in
a solution of nitre and dry it again. It is now so explosive that
great care is required in its management, being about three times
as explosive as gunpowder.