will have a low nitrogen content, whereas a material with as high a
nitrogen as 12 or 12.6 is to be aimed at.

[Footnote A: Raw cotton is often used.]

The cotton should not be allowed to remain in the dipping tanks for more
than five minutes, and the acid mixture should be kept at a temperature of
28° C. or thereabouts; and the cotton should be removed after a few
minutes, and should not be pressed out, as in the 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:--