case of gun-cotton, but
at once transferred to the pots and allowed to steep for forty-eight
hours. (Some prefer twenty-four hours, but there is more chance in this
case of the product containing non-nitrated cellulose.) When the nitration
is complete, the collodion-cotton is removed from the pots, and treated in
exactly the same manner as described under gun-cotton. The produce should
be entirely soluble in ether-alcohol and nitro-glycerine, and contain as
near 12.7 per cent. of nitrogen as possible. The theoretical nitrogen is
for the penta-nitro-cellulose 12.75 per cent. This will, however, seldom
if ever be obtained. The following are some of the results I have obtained
from different samples:--

Nitrogen.
(1.) (2.) (3.)
German make 11.64 11.48 11.49 per cent.
Stowmarket 12.57 12.60 11.22 "
Walsrode 11.61 12.07 11.99 "
Faversham 12.14 11.70 11.60 "

and the following was the analysis of a sample (No. 1) of German-made
collodion-cotton, which made very good blasting gelatine:--

_
Soluble cotton (collodion) 99.118 per cent.| Nitrogen = 11.64 per cent.
Gun-cotton 0.642 " _|
Non-nitrated cotton 0.240 "
Total ash 0.25 "

It should contain as little non-nitrated or unconverted cotton and as
little gun-cotton as possible, as they are both insoluble in nitro-
glycerol. The quality and composition of any sample of collodion-cotton
can be quickly inferred by determining the percentage of nitrogen by means
of the nitrometer and the use of the solubility test.[A] A high nitrogen
content coupled with a high solubility is the end to be aimed at; a high
nitrogen with a low solubility shows the presence of gun-cotton, and a low
nitrogen, together with a low solubility, the presence of unnitrated
cotton. Where complete solubility is essential and the percentage of
nitrogen less important, Dr Lunge recommends nitration with a mixture of
equal parts of sulphuric and nitric acids containing from 19 to 20 per
cent. of water.

[Footnote A: See Analysis of Explosives.]

Mr T.R. France claims to have invented some improvements in the
manufacture of soluble nitro-cellulose. His object has been to produce an
article as uniform as possible. His explanation of the imperfect action of
the acids is that, however uniform the mixed acids may be in strength and
proportions, and ho