Improvements in Disinfecting, and in Apparatus therefor.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Disinfecting, and in Apparatus therefor.
I, AUGUST ZIMMERMANN, of 9 and 10 St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been communi-
cated to me from abroad by The Chemische Fabrik auf Actien vormals E. Schering, of
170 and 171 Müllerstrasse, Berlin, in the Empire of Germany,) to be as follows:-
If dry paraformaldehyd is heated by itself, upon a metal plate for example, it slowly
dissociates to formic aldehyd. At a certain distance from the heated plate the vapours
however easily condense again to paraformaldehyd. By this means therefor it is
impossible to diffuse formic aldehyd in a large room and the more so if no energetic
circulation of air takes place. Disinfection in the manner suggested is also wholly
insufficient and unsuitable because only a feeble disinfecting action is obtained
by employing dry paraformaldehyd. It can be proved that formic aldehyd only
develops an energetic disinfecting action when possessing a certain degree of
moisture.
According to this invention a disinfecting lamp is employed which is so constructed
as to bring the formic aldehyd vapour evolved by heating paraformaldehyd into a
finer state of division by mixture with the products of combustion and to give it at
the same time the necessary degree of moisture. These two conditions are necessary
for rationally and thoroughly disinfecting by means of formic aldehyd.
It is preferred to construct the apparatus in the following manner :- Two co-axial
tubes are employed the outer one being closed at the top the inner tube projects
through its cover. The inner tube is closed at its lower end and has in it slit like
holes opening into the space between the tubes near the top of the outer one. This
inner tube which is heated by a source of heat placed below it for example by means
of a spirit lamp, serves as the receptacle for the paraformaldehyd, preferably in the
form of pastils.
In order that the paraformaldehyd may not be gasified too quickly, asbestos or
other wire may be placed in the inner tube in order to somewhat moderate the quick
equalisation of temperature from the outside to the inside. In order also that the
vapourisation of the paraformaldehyd may be regulated according to the object
required, an arrangement may be placed in the inner tube for the reception of the
pastil of paraformaldehyd, which may be raised to the required distance from the source
of heat. Or the wick may be provided with a screw arrangement by which the flame
may be regulated as desired.
This object may also be very easily attained by placing a metal plate between the
flame and the tube which can be turned to any required angle to the flame by means
of a handle reaching outwards. At the full horizontal position of this plate the
paraformaldehyd is slowly gasified as the flame does not play directly upon the bottom
of the tube but upon the metal plate placed between. If it be desired to gasify
somewhat more quickly, the plate is turned obliquely to the flame. When the plate
is vertical the flame comes almost full upon the bottom of the tube.
The action of the lamp is easily understood. The products of combustion heat the

page_text: pastils in the tube, and pass up the space between the two tubes, through the slit
like holes, into the top of the inner tube taking up the vapours of formic aldehyd
evolved and bringing these into a very fine state of division and energetic
circulation. It is important to so far cool the gases of combustion by a suitable
adjustment of tubes that their temperature is below the ignition temperature
of the formic aldehyd gases, otherwise the gas would naturally commence to burn.
It is of special importance in this apparatus that a great quantity of moisture
should be brought by the products of combustion to the formic aldehyd. To gasify
a pastil of formic aldehyd of 1 grain weight at least 3 grains of spirit are necessary;
these 3 grains of spirit produce about 3 grains of water.
It is as has already been remarked only upon the introduction of moisture that
it is possible to bring into action in the required measure the disinfecting action of
the formic aldeltyd.
By mixture with the gases of combustion the formic aldehyd is also brought to an
exceedingly fine gaseous state of division as appears from the following:-3 grams of
spirit produce nearly 9 grams of carbonic acid so that the formic aldehyd evolved
from 1 gram of paraformaldehyd will be mixed with 9 grams of carbonic acid and
about 3 grams of steam. Besides this however a great quantity of air is mixed
with the formic aldehyd vapours by the suction action caused by the draught of the
products of combustion.
The paraformaldehyd may of course be mixed, if desired with any other disinfecting
or sweet scented substance.
The disinfecting lamp described may not only be used for disinfecting rooms but
also for the disinfection of all possible articles, as for example for disinfecting
bandages, surgical instruments and the like. In this case the lamp may with
advantage be so arranged that the upper end of the tube from which the disinfecting
gases pass out is connected with a receiver in which the articles to be disinfected are
placed.
Dated this 24th day of November 1896.
Improvements in Disinfecting, and in Apparatus therefor.
I, AUGUST ZIMMERMANN, of 9 and 10 St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been communicated
to ine from abroad by The Chemische Fabrik auf Actien vormals E. Schering, of
170 and 171 Müllerstrasse, Berlin, in the Empire of Germany,) and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
If dry paraformaldehyd is heated by itself upon a metal plate for example, it slowly
dissociates to formic aldehyd. At a certain distance from the heated plate the vapours
however easily condense again to paraformaldehyd. By this means therefore it is
impossible to diffuse formic aldehyd in a large room and the more so if no energetic
circulation of air takes place. Disinfection in the manner suggested is also wholly
insufficient and unsuitable because only a feeble disinfecting action is obtained by
employing dry paraformaldehyd. It can be proved that formic aldehyd only develops
an energetic disinfecting action when possessing a certain degree of moisture.
According to this invention a disinfecting lamp is employed which is so constructed
as to bring the formic aldehyd vapour evolved by heating paraformaldehyd into a finer
state of division by mixture with the products of combustion and to give it at the
same time the necessary degree of moisture. These two conditions are necessary
for rationally and thoroughly disinfecting by means of formic aldehyd.

page_text: It is preferred to construct the apparatus in the following manner :-Two co-axial
tubes are employed, the outer one being closed at the top, the inner tube projects
through its cover. The inner tube is closed at its lower end and has in it holes opening
into the space between the tubes near the top of the outer one. This inner tube which
is heated by a source of heat placed below it, for example by means of a spirit lamp,
serves as the receptacle for the paraformaldehyd, preferably in the form of pastils.
The form of lamp preferred is shown in elevation in Figure 1, the upper part of
the chimney cap being broken away to show the receptacle for the disinfectant.
« is an ordinary spirit lamp with burner a', and chimney b, provided with a cap b',
which supports at a sufficient distance above the flame a metal receptacle or cup c
in which the paraformaldehyd is placed. This cup may be lined with wire gauze d
and is provided with openings e which form the only means of exit for the products
of combustion of the lamp which are thus compelled to mingle with the aldehyd
vapour before the latter leaves the cup.
Figure 2 shows an alternative form of cup.
In order that the paraformaldehyd may not be gasified too quickly, asbestos or other
wire may be placed in the inner tube in order to somewhat moderate the quick
equalisation of temperature from the outside to the inside. In order also that the
vanurisation of the paraformaldehyd may be regulated according to the object
required, an arrangement may be placed in the inner tube for the reception of the
pastil of paraformaldehyd which may be raised to the required distance from the
source of heat. Or the wick may be provided with a screw arrangement by which
the flame may be regulated as desired.
This object may also be very easily attained by placing a metal plate between the
flame and the tube which can be turned to any required angle to the flame by means
of a handle reaching outwards. At the full horizontal position of this plate the
paraformaldehyd is slowly gasified as the flame does not play directly upon the bottom
of the tube but upon the metal plate placed between. If it be desired to gasify
somewhat more quickly, the plate is turned obliquely to the flame. When the plate
is vertical the flame comes almost full upon the bottom of the tube.
The action of the lamp is easily understood. The products of combustion heat
the pastils in the tube, and pass up the space between the two tubes, through the
holes, into the top of the inner tube taking up the vapours of formic aldehyd evolved
and bringing these into a very fine state of division and energetic circulation. It is
important to so far cool the gases of combustion by a suitable adjustment of tubes
that their temperature is below the ignition temperature of the formic aldehyd gases,
otherwise the gas would naturally commence to burn.
It is of special importance in this apparatus that a great quantity of moisture should
be brought by the products of combustion to the formic aldehyd. To gasify a pastil
of formic aldehyd of 1 grain weight at least 3 grains of spirit are necessary; these
3 grains of spirit produce about 3 grains of water.
It is as has already been remarked only upon the introduction of moisture that it
is possible to bring into action in the required measure the disinfecting action of the
formic aldehyd.
By mixture with the gases of combustion the formie aldehyd is also brought to an
exceedingly fine gaseous state of division as appears from the following:-3 grams of
spirit produce nearly 9 grams of carbonic acid so that the formic aldehyd evolved
from 1 gram of paraformaldehyd will be mixed with 9 grams of carbonic acid and
about 3 grams of steam. Besides this however a great quantity of air is mixed with
the formic aldehyd vapours by the suction action caused by the draught of the
products of combustion.
The paraformaldehyd may of course be mixed, if desired with any other disinfecting
or sweet scented substance.
In place of paraformaldehyd any other body (such for example as asbestos saturated
with an aqueous solution of formic aldehyd) which on heating gives off formic aldehyd
vapour may be employed.
The disinfecting lamp described may not only be used for disinfecting rooms but

page_text: also for the disinfection of all possible articles, as for example for disinfecting bandages,
surgical instruments and the like. In this case the lamp may with advantage be so
arranged that the upper end of the tube from which the disinfecting gases pass out is
connected with a receiver in which the articles to be disinfected are placed.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. Making formic aldehyd by heating paraformaldehyd or other substance producing
formic aldehyd and mixing the vapour with products of combustion.
2. The combination of a burner and a receptacle with means for leading the
products of combustion to the top of the receptacle.
3. Lamps substantially as described and shown in the drawings.