An Improved Preparation of Formic Aldehyde and Disinfecting thereby.
Year: 1899

page_text: Date of Application, 19th Apr., 1899
Complete Specification Left, 18th Jan., 1900-Accepted, 24th Feb.,
1900
INUYIDIONAL DIECIFICATION.
An Improved Preparation of Formic Aldehyde and Disinfecting
thereby.
I, CHARLES 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 com-
municated 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:-
This invention relates to a novel method of disinfecting by means of formic
aldelyde, in which all troublesome apparatus, and the use of an outside source of
heat, is avoided, and which is therefore from a technical standpoint distinguished
by the greatest simplicity, cheapness and ready adaptability without any risk
of fire.
The method consists in mixing polymerized formic aldehyde, paraformaldehyde
for example, or other body or liquid containing or producing formic aldehyde,
with quicklime or other suitable alkaline earth, or with caustic alkali, or with
substances which react with water with great evolution of heat, and then allowing
water to react on the mixture.
By the use of quicklime, which in practice is especially successful, the heat
evolved is so considerable that a great portion of the excess of added water
passes away as steam, and from the body giving off formic aldehyde which is
added or mixed with the quicklime the gaseous formic aldehyde is evolved extra-
ordinarily quickly and nearly exhaustively.
By this method everything required for thorough disinfection by means of
formic aldehyde is obtained in a very simple and self acting manner.
The space to be disinfected is quickly filled with the necessary quantity of
formic aldehyde and a large amount of steam is simultaneously supplied.
Very good results are attained with a mixture of quicklime with polymeric
formic aldehyde (for example paraformaldehyde) which mixture may be pressed
It is then only
into pastilles or larger pieces and in this form are ready for use.
necessary for disinfecting or deodorizing a space, to add to the said mixture in
the form supplied, after if necessary reducing the size of the pieces, with the
proper quantity of water, whereupon after a very short time a lively evolution of
steam and formic aldehyde takes place. The use of warm water is preferable.
The great advantages of this method of disinfecting are that :-
1. No special apparatus is required.
2. The use of fuel as source of heat is unnecessary.
3. The exact dosing of the disinfectant is rendered easy.
4. The process is very cheap.
5. Steam is automatically evolved.

page_text: In place of polymerized formic aldehyde, one may, as already stated, use other
bodies or liquids producing formic aldehyde in combination with quicklime, as
for example, formic aldehyde solution, or a compound easily splitting up into
formic aldehyde, or bodies through whose mutual action formic aldehyde is
produced.
When formic aldehyde solution, which is also very suitable for carrying out the
method, is used, one should proceed by mixing the quicklime, preferably in the
form of large grains, with the necessary amount of formic aldehyde solution,
and then diluting with water. The reaction then proceeds as when polymerized
formic aldehyde is used.
T
1
* 11.
COMPLETE SPECIFICATION.
An Improved Preparation of Formic Aldehyde and Disinfecting
thereby
L
. +
I, CHARLES 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 com-
municated to me 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: —
This invention relates to a novel method of disinfecting by means of formic
aldelyde, in which all troublesome apparatus, and the use of an outside source of
heat, is avoided, and which is therefore from a technical standpoint distinguished
by the greatest simplicity, cheapness and ready adaptability without any risk
of fire.
The method consists in mixing polymerized formic aldehyde, paraformaldehyde
for example, or other body or liquid containing or giving off formic aldehyde,
with quicklime or other suitable alkaline earth, or with caustic alkali, or with
substances which react with water with great evolution of heat, and then allow-
ing water to react on the mixture. In using an aqueous formic aldehyde solution,
it is not necessary to specially add water as the formic aldehyde solution already
contains water.
By the use of quicklime, which in practice is especially successful, the heat
evolved is so considerable that a great portion of the excess of added water passes
away as steam, and from the body giving off formic aldehyde which is added or
mixed with the quicklime the gaseous formic aldehyde is evolved in about 10
minutes. If warm water be used the evolution of course takes place more quickly.
By this method everything required for disinfection by means of formic alde-
hyde is obtained in a very simple and self acting manner.
The space to be disinfected is quickly filled with the necessary quantity of
formic aldehyde and a large amount of steam is simultaneously supplied.
Good results are, for instance, attained with a mixture of quicklime with poly-
meric formic aldehyde (for example paraformaldehyde) which mixture may be
pressed into pastilles or larger pieces and in this form are ready for use.
It is of course not necessary to bring the polymeric formic aldehyde into
intimate mixture with quicklime, one may proceed by shaking the formic alde-
hyde over the quicklime and then adding water, or water is first added to the

page_text: quicklime and then polymeric formic aldehyde spread over it. In all cases the
heat produced by slacking the lime drives the formic aldehyde out from the
substance evolving the formic aldehyde. It is not necessary that the body evolv-
ing formic aldehyde should be in direct contact with the quicklime or the like
but the substance may for example be placed a short distance above the quick-
lime in a suitable manner so that the steam produced by the action of the water
upon the quick-lime passes the body evolving the formic aldehyde and carries it
with it.
In place of polymerized formic aldehyde one may, as already stated, use other
bodies or liquids giving off formic aldehyde, as for example, formic aldehyde solu-
tion, or a compound easily splitting up into formic aldehyde, or bodies through
whose mutual action formic aldehyde is produced.
When aqueous formic aldehyde solution, which is also very suitable for carry-
ing out the method, is used, one should proceed by mixing the quicklime either
in the form of large grains or in the form of powder, with the necessary amount
of formic aldehyde solution, eventually diluting with water. The reaction then
proceeds as when polymerized formic aldehyde is used.
It is agreeable to the purpose and in other ways preferable if some substance
is added which quickens the action of water on quicklime. Such substances are
for instance the chlorides of the alkaline earth, for example barium chloride, or
some acid such as hydrochloric acid, nitric acid, acetic acid, lactic acid, or sodium
acetate, asparagin, or ethylalcohol.
Or instead of the addition of substances quickening the operation substances
are added which neutralize the chemical action of the quicklime on the formic
aldehyde on slaking the lime.
The addition of such substances which neutralize the decomposing action of the
lime upon the formic aldehyde is to be recommended as thereby a better utiliza-
tion of the formic aldehyde for disinfecting action is produced. Such substances
are oxalic acid and sulphuric acid.
When using oxalic acid one proceeds for example as follows in order to properly
disinfect a space of 100 cubic centimetres.
3 kilograms quicklime are mixed with 6 kilograms oxalic acid and 1.2 kilo-
grams formic aldehyde 40% solution to which 2.5 kilograms water has been added
thereto. In a few minutes a lively evolution of formic aldehyde takes place and
so much formic aldehyde is evolved that there are 4 grains formic aldehyde per
cubic centimetre space.
The great advantages of the described method of disinfecting are that:-
1. No special apparatus is required.
2. The use of fuel as source of heat is unnecessary.
3. The exact dosing of the disinfectant is rendered easy.
4. The process is cheap.
5. Steam is automatically evolved.
6. A thorough disinfection is obtained in the easiest possible manner.
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. A preparation consisting of a solid material containing or producing formic
aldehyde mixed with quicklime or the like.
2. The process of disinfecting by means of formic aldehyde consisting in
bringing a substance giving off formic aldehyde into contact with water and
quicklime or other substance which reacts with water with great evolution of
heat whereby a stream of gaseous formic aldehyde mixed with steam is produced.
3. In the process claimed by Claim 2 the employment of substances which
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. A preparation consisting of a solid material containing or producing formic
aldehyde mixed with quicklime or the like.
2. The process of disinfecting by means of formic aldehyde consisting in
bringing a substance giving off formic aldehyde into contact with water and
quicklime or other substance which reacts with water with great evolution of
heat whereby a stream of gaseous formic aldehyde mixed with steam is produced.
3. In the process claimed by Claim 2 the employment of substances which
hasten the reaction between water and quicklime or which prevent the chemical
action of the lime upon the formic aldehyde.

page_text: 4. The use of the heat produced by the action of water upon quicklime and
like substances for evolving formic aldehyde from substances giving off formic
aldehyde.