An Improvement in the Treatment of Nitrocellulose.
Year: 1898

page_text: Date of Application, 3rd Sept., 1898
Complete Specification Left, 30th May, 1899--Accepted, 1st July, 1899
PROVISIONAL SPECIFICATION.
An Improvement in the Treatment of Nitrocellulose.
We, ALFRED LUCK, of Brencote, Dartford, Kent, Chemist, and CHARLES
FREDERICK CRoss, of 4, New Court, Carey Street, in the County of London,
Chemist, do hereby declare the nature of this invention to be as follows:-
"
To make ordinary guncotton or other forms of nitro-cellulose sufficiently stable
to stand the well known heat test," it is necessary to employ considerable time
in boiling and washing the material, and the results usually obtained are not
so good as is desirable.
This invention relates to means of producing the effect of stability of the nitro-
cellulose in considerably less time than is usually required, and of attaining
greater stability, that is to say, to make the nitro cellulose capable of standing
the heat test for a considerably longer period.
..
For this purpose, after freeing the gun-cotton from any acid adhering to it from
the nitration process, we boil it with a dilute solution of "the salts of certain metals
preferably the "heavy metals" such for instance as lead acetate or zinc chloride.
After a comparatively short period of boiling, the desired effect of being able to
stand the "heat test" is thus attained and the guncotton, instead of being able to
stand this test as it usually does for only about ten minutes, can, after this treat-
ment, stand the test for a considerably longer period. Some forms of nitro-cellulose,
such as collodion cotton, do not require to be boiled with the solution of the salt,
but only to be heated to a moderate degree, such as 50° or 60° C.
at this 2nd day of Sontomber 1898
ABEL & IMRAY,
Agents for the Applicants.
An Improvement in the Treatment of Nitrocellulose.
We, ALFRED LUCK, of. Brentcote, Dartford, Kent, Chemist, and CHARLES
FREDERICK CROss, of 4, New Court, Carey Street, in the County of London,
Chemist, do hereby declare. the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
Our invention relates to a process for rendering cellulose nitrates stable, this
process being based upon observation of the nature and properties of impurities
eliminated from nitrocellulose under the action of diluted solvents especially those
of the high nitrates. The solutions thus obtained, when freed from any dissolved
nitrate of cellulose: by further dilution and filtration, are found to contain an
acid substance or substances which unites with metallic bases such as lead oxide,
forming insoluble compounds. These precipitates, when dried and analysed, are
го

page_text: found to contain a high proportion of the metallic oxide for example 40
to 50 per cent. of PbO, and they also contain "Nitric Nitrogen," for instance
3 per cent. N which gives them the characteristics of explosive bodies. It appears
that when these acid compounds, which are present in the original guncotton,
are combined with basic oxides they are rendered relatively inert and incapable
of upsetting the stability of the gun-cotton.
This result is brought about by treating the cellulose nitrates with solutions
of the metallic salts. These may be dilute aqueous solutions; or the action may
be carried out in the presence of acetone.
When no acetone is present the guncotton after being purified more or less
by the ordinary process is digested at 80° to 100° C., with sufficient quantity of
about 1 per cent. solution of lead acetate, or zinc acetate, to entirely cover the
guncotton. After sufficient time for completion of the action the excess of
solution is removed and the nitrate is thoroughly washed until it is free from all
traces of the soluble metallic salt. Or the guncotton may be covered with acetone
diluted by twice or thrice its weight of water, and containing also the metallic
salt in 1 per cent. solution that is added to the extent of about 1 per cent. by
weight of the diluted acetone. The process in this case is completed at ordinary
temperature, in about half an hour and then the solution is drained off and the
nitrate is washed with water in successive small quantities until the bulk of the
acetone is removed; the wash waters being retained for the recovery or further
use of the acetone. The product is then exhaustively washed.
The product of the treatment retains about 2 per cent. of the basic oxide (PbO)
in combination with the acid groups before mentioned. We have obtained pro-
ducts showing satisfactory stability by treating cellulose nitrates with salts of
lead, zinc, cadmium, calcium barium, magnesium, and other metals. The most
satisfactory results are obtained by using zinc, magnesium, and lead salts. We
prefer to use the salts of these metals with acids of low hydrolysing function,
such as acetic acid.
We are aware that certain metallic compounds have been used in association
with guncottons with a view to increase their stability; of these we may instance
calcium and magnesium carbonates which are in some cases added for the purpose
to the explosive nitrate, but more often find their way into the product as the
result of the boiling and washing with ordinary water.
Mercuric chloride has also been added to guncottons and the presence of this
salt has been assumed to raise the stability of the explosive. But this conclusion
has been shewn to result from an interference of the mercury salt with the
chemical reactions involved in the usual "heat test."
These facts are fully set forth in the recent publications of Simon Thomas
(Zeitschrift Augewandte Chemie for 1898, pp. 1003-6 and 1027-31) which con-
tains however no suggestion of the presence of such acid compounds in guncottons,
as we have particularised, nor of such treatment as we propose with metallic salts
for the purpose of bringing them into a relatively inert form by combination with
basic metallic oxides.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, we declare that what
we claim is :-
-
A process for increasing the stability of nitrocellulose by freeing the nitro-
cellulose from the nitrating acid and treating it with a solution of a salt of a
heavy metal such as lead acetate, or zinc chloride, substantially as described.
ABEL & IMRAY,
Agents for the Applicants.