A New and More Economical Method for the Production of Nitrous Oxide.
Year: 1891

page_text: Date of Application, 27th May, 1891
Complete Specification Left, 26th Feb., 1892-Accepted, 21st May, 1892
PROVISIONAL SPECIFICATION.
A New and More Economical Method for the Production of
Nitrous Oxide.
We, WATSON SMITH, Lecturer in Chemical Technology, University College,
London, and WILLIAM ELMORE, Electro-metallurgist, 47 Clapham Road, S. W.
do hereby declare the nature of this invention to be as follows:-
This invention has for its object the manufacture of nitrous oxide gas otherwise
known as "laughing-gas," for anaesthetic purposes or other or similar purposes, by
a new method and in a more economical manner than heretofore. This method
consists in simply heating a mixture of equivalent weights of nitrate of sodium or
potassium and sulphate of ammonium, when the mixture soon commences to melt
and to evolve gas. The salts taken should be as dry as possible, and the retort or
other suitable heating vessel so arranged that any moisture condensing may not
fall back into the heated mass in the heating vessel or retort but rather run off
down the retort stem, or elsewhere. The evolution of gas proceeds smoothly and
rapidly and only needs a little washing by passing it through a solution of an
alkali and afterwards through one of dilute sulphuric acid or, washing or scrubbing
in a suitable washer or scrubber with a suitable alkaline solution or even with warm
water alone, may suffice. It may be purified, or further purified if desired, by
any other known method, and then subjected to compression with or without
previous or simultaneous cooling in any suitable apparatus for purposes of storage,
transport, or employment as an anesthetic or otherwise.
It is of course possible to modify the process by fusing the nitrate of sodium and
potassium in a suitable apparatus and to add the sulphate of ammonium little by
little, but we prefer the simpler method of heating the mixture.
The yield of nitrous oxide gas by the action of heat upon the mixtures herein
specified, is but very little behind that obtained by the action of heat on equivalent
amounts of ammonium nitrate in the usual way.
The proportions to be taken are about the following; 17 parts by weight of
nitrate of soda or 20-2 of nitrate of potassium along with 13-2 of sulphate of
ammonium, all as dry as possible The respective weights of the mixture whether
nitrate of sodium or nitrate of potassium be taken, will thus be for the first 30.2
parts of the nitrate of sodium mixture and 33-4 parts of the nitrate of potassium
mixture.
These weights of the mixtures named will be cach equivalent theoretically to
16 parts by weight of nitrate of ammonium.
As a matter of experience it is found best to use in the mixtures named, the
sulphate of ammonium slightly in excess.
Dated this 27th day of May 1891.
WATSON SMITH.
WILLIAM ELMORE.
COMPLETE SPECIFICATION.
A New and More Economical Method for the Production of
Nitrous Oxide.
We, WATSON SMITH, Lecturer in Chemical Technology, University College
London, and WILLIAM ELMORE, Electro-metallurgist, of Worcester House
Walbrook E.C., do hereby declare the nature of this invention and in whe
Price 887

page_text: manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention has for its object the manufacture of nitrous oxide gas, otherwise
known as "laughing gas" in a more economical manner than that in which it has
hitherto been produced from the comparatively expensive ammonium nitrate.
In carrying out our invention we mix together about 17 parts by weight of
commercial sodium nitrate or about 20 parts of potassium nitrate with from
13 to 14 parts of ammonium sulphate, taking care that these substances are quite
dry, and we heat the mixture in a retort or other suitable vessel to a temperature
which, by preference, during the greater part of the reaction should not exceed
230° C. but which towards its termination may rise to 300°. The retort or vessel
employed and the passage for the gas from it should be so arranged that moisture
that might casually be deposited from the escaping gas should not return to the
heated materials. Instead of mixing the nitrate and the sulphate in the first
insterce, the nitrate may first be fused and the sulphate added to it in successive
doses, but the treatment first described is greatly to be preferred.
The gas evolved from the retort or vessel may be cooled, scrubbed or otherwise
purified in any known manner. In order to eliminate any alkaline or acid matter
that might pass over with it, we prefer to pass the cooled gas through weak acid
and alkaline solutions.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :
The herein described manufacture of nitrous oxide gas by heating dry sodium
or potassium nitrate with dry ammonium sulphate.
Dated this 26th day of February 1892.
ABEL & IMRAY,
Agents for the Applicants.