Improvements in and relating to General Anaesthetics.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in and relating to General Anaesthetics.
ROBERT MARSTON, Palissy House, Narborough Road, Leicester, in the County
of Leicester, Dental Surgeon, I do hereby declare the nature of this invention
to be as follows:-
My invention has for its object the causing of insensibility to pain, during
surgical operations, otherwise than by the inhalation of such poisons as chloro-
form, ether, and other narcotics, commonly used for producing general anæs-
thesia.
The agent I use for this purpose is partially reduced or de-oxygenated atmo-
spheric air, or its equivalent, namely, perfectly reduced or de-oxygenated atmo
spheric air mixed with variable proportions of normal atmospheric air added
thereto for the purpose of retarding and otherwise modifying that physiological
action (oxygen starvation) which results from inhaling any negative asphyxiant.
This partially, or completely, de-oxygenated atmospheric air I prepare for this
specific purpose by any of the numerous processes practised by chemists and
others for separating the constituents of the common atmosphere, in their experi-.
mental, analytical, and manufacturing pursuits: for instance, this agent results
as a waste bye-product from the manufacture of sulphurous acid; from the
manufacture of ozonised compounds; from the manufacture of pigments, such
as metallic oxides; sulphates; phosphates; and from other processes having for
their object, the combustion, or the oxidation of organic or in-organic sub-
stances. If immediate administration of this agent, to a patient, is intended a
less productive and more convenient apparatus and method are adopted than
those required for producing, "recovering" and collecting this agent on a com-
mercial scale for wholesale distribution amongst dentists, and surgeons, at home,
and abroad.
My invention, therefore, relates to and embraces the collection, the produc-
tion, and the use of partially "reduced" or de-oxygenated atmospheric air and
its equivalent namely perfectly reduced" or deoxygenated atmospheric air
mixed with normal atmospheric air as herein before described for the purpose
hereinbefore specified.
My invention also relates to and embraces all suitable. means for compressing
and storing this agent for surgical requirements whether for immediate use or
for transport and general distribution.
Dated this 22nd day of February 1899.

page_text: improvements in ag towers
ROBERT MARSTON, Palissy House, Narborough Road, Leicester, in the County
of Leicester, Dental Surgeon, I 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:-
.
My invention has for its object the causing of insensibility to pain during
surgical operations otherwise than by the inhalation of such poisons as chloro-
form ether and other narcotics, commonly used for producing general, antes-
thesia.
as
The agent I use for this purpose is partially reduced or de-oxygenated atmo-
spheric air, or its equivalent namely perfectly reduced or de-oxygenated atmo-
spheric air mixed with variable proportions of normal atmospheric air added
thereto for the purpose of retarding and otherwise modifying that physiological
action (oxygen starvation) which results from inhaling any negative asphyxiant.
This partially - or completely de-oxygenated atmospheric air I prepare for this
purpose by any and all of the numerous-processes practised by chemists and
others for separating the constituents of the common atmosphere in their experi-
mental, analytical and manufacturing pursuits. For instance this agent results
as a waste bye product from the manufacture of sulphurous acid from the manu-
facture of ozonized compounds: from the manufacture of pigments such
metallic oxides sulphates, phosphates and from other processes having for their
object the combustion or the oxidation of organic or inorganic substances. If
this agent is required for immediate administration to a patient it would be pro-
duced by a more convenient apparatus and less productive method than those
required for the producing collecting and storing of this agent on a commercial
scale such for instance as is suitable for its wholesale distribution among
dentists and surgeons throughout the kingdom and abroad. Preferably I pre-
pare this anaesthetic agent by passing atmospheric air (which has been freed
from carbonic acid and impregnated with ammonia or an ammoniacal compound
or with its equivalent proportion of hydrogen or any substance capable of yield-
ing the same) through one or more properly heated tubes, retorts, or other suit-
able receptacles containing copper iron or any other oxidisable or peroxidisable
substance or any substance impregnated with or superficially coated with any
substance which is capable of inducing chemical combination when atmospheric
air and ammonia, hydrogen or substances containing the same are passed together
or alternately over its heated surface. During its passage through the retorts
or other suitable receptacles the oxygen of the atmosphere leaves the nitrogen
and combines with the oxidisable metal to form an oxide, or with the peroxi-
disable substance to forming a peroxide which in the presence of ammonia,
hydrogen, or substances capable of yielding the same, becomes reduced through
its separable oxygen combining with the hydrogen of the ammonia, or its equi-
valent, to form water.
During this reaction a percentage of oxygen may combine with a portion of
the nitrogen to form various oxides of nitrogen some of which are of a highly
deleterious nature and must therefore either be removed or else converted into
that nitrogen compound which is distinguished by the name nitrous oxide, the
presence of which in the atmospheric nitrogen is beneficial because owing to its
density and solubility in the blood it broadens the workable zone of the atmo

page_text: spheric nitrogen. For this reason I convert these noxious compounds of nitro-
gen into nitrous oxide by treating them with those agents which are commonly
known to be capable of converting them into that gas but which have never
been applied to the purposes of this my invention. For instance by conducting
the gas from the retorts or receptacles, herein before mentioned, through moistened
iron shavings, scraps of copper zinc or other suitable metals, sulphides or sul-
phites in liquid or solid form, or through other oxedisable or reducing sub-
stances, the nitric oxide present in the now changed atmospheric air becomes
reduced to nitrous oxide.
"
Instead of reducing the nitric oxide I sometimes convert it into a higher
oxide of nitrogen and by subsequently adding ammonia to the passing gas before
it reaches the cooling apparatus, nitrate of ammonia is formed which owing to
the maintenance of a proper temperature splits up into nitrous oxide and water."
I sometimes create ammoniacal compounds in the gas that comes over by
mixing a larger proportion of ammonia with the atmospheric air whilst passing
through the retorts. These expedients, however are equivalent to each other in
practice, each having for its object the conversion of noxious nitrogen com-
pounds present in the gas when it leaves the retorts, into nitrous oxide. After
that treatment I pass the current of gas through a solution of sulphate of iron
or other equivalent reagent in solid or liquid form or absorbed by porous bodies
is
contained in one or more closed vats or other vessels and after that the gas
passed through an alkaline solution in order to remove the last trace of any
deleterious impurity.
The gas now chiefly' atmospheric nitrogen freed from available oxygen is then
conducted to the gas-holder which is connected with one or more compressors,
which pump the gas into cylinders ready for use.
It will appear self evident from what has been said, that mixtures of ammonia
and air could not be made satisfactorily unless suitable means were used for
proportioning them, nor would the mixture so formed pass through the retorts
cooler, purifiers and washers unless driven or drawn. It is, therefore, necessary
for me to explain that when I use compressed ammonia gas. contained in
cylinders I connect the outlet of the cylinder with my apportionator Patent
17237 A.D. 1898 which automatically and correctly maintains the desired pro-
portions of ammonia and air which may be varied according to the dryness of
the gas or the presence of aqueous vapour. Instead of using the apportionator
I sometimes attach what is commonly called a gas regulator to the cylinder
from which a regular stream of ammonia flows into the inlets of the retorts and
the necessary proportion of air is pumped in by the compressors.
When liquid ammonia is used I put it into a suitable reservoir provided with
an ammonia pressure gauze a tube connected with the inlet of the retort
descends nearly to the bottom of this reservoir and when compressed air is forced
into the space above the surface of the liquid ammonia, the latter is driven up
the tube at a rate which is regulated by the stopcock whose function it is to
govern the outflow.
Sometimes I generate the ammonia gas and the pressure for driving it over,
by dribbling a solution of ammonium sulphate on quicklime contained in a
strong vessel. The outflow of gaseous ammonia, into the retorts is regulated
whilst the compressors supply the necessary quantity of atmospheric air.
These different ways of conducting my process aim at producing atmospheric
nitrogen free from available oxygen, although it may contain the nitrogen com-
pound called nitrous oxide.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. The sole right to make de-oxygenated atmospheric air for surgical

page_text: 2. The process of producing de-oxygenated atmospheric air containing nitrous
oxide substantially as and for the purpose above described.
3. The sole right to use the process and the equivalent expedients which it
embraces, for this purpose as herein before set forth.
Dated this 22nd day of November 1899.