Improvements in the Production of Formic Aldehyde Vapours.
Year: 1896

page_text: Date of Application, 4th Dec., 1896
4007
Assorted 0th Oct
1807
PROVISIONAL SPECIFICATION.
Improvements in the Production of Formic Aldehyde Vapours.
A Communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHÔNE, anciennement GILLIARD P. MONNET ET CARTIER, of Lyons, France,
Manufacturers.
1, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn & Ellis of 55 and 56
Chancery Lane, in the County of London, Chartered Patent Agents, do hereby
declare the nature of this invention to be as follows:-
This invention consists in the production of formic aldehyde vapours from
trioxymethylene or other solid polymeric modifications of formic aldehyde more
particularly for the purposes of disinfection.
It is already known that pure formic aldehyde vapours can be obtained from the
commercial formic aldehyde solution by means 'of heating in suitable apparatus
under pressure, preferably in the presence of neutral salts, as for instance calcium
chloride in the solution.
My foreign correspondents have discovered that this method for the production
of formic aldehyde vapours may be extended to the employment of trioxy-
methylene or other solid polymeric modifications of formic aldehyde in place of the
commercial solution. For this purpose and according to the present invention
the trioxymethylene (or other solid polymer of formic aldehyde) is mixed with
water, to which neutral salts may be added, and heated under pressure. On
warming the trioxymethylene dissolves and as the temperature increases becomes
dissociated and pure formic aldehyde vapours are generated; this dissociation is
most complete at a temperature of about 130° or 135° C. although it commences
to take place at a lower temperature.
In order to carry out the invention any suitable autoclave capable of with-
standing 5 or 6 atmospheric pressures, such as is employed for the generation of
formic aldehyde vapours from the commercial solution may be used. As compared
with the latter method of generating formic aldehyde vapours from the commercial
solution, the new process has the advantage that trioxymethylene or other polymers
of formic aldehyde being in solid form are much more convenient for transport
and manipulation. It is also possible in this way to generate in an equal time a
much larger quantity of pure formic aldehyde vapours, which is very desirable in
the disinfection of large rooms or buildings where it is always difficult to secure
perfect enclosure.
11906

page_text: A
COME FREE DE MOLTIVATION.
Improvements in the Production of Formic Aldehyde Vapours.
Communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHÔNE, anciennement GILLIARD P. MONNET ET CARTIER, of Lyons, France,
Manufacturers.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn & Ellis of 55 and 56
Chancery Lane in the County of London, Chartered Patent Agents, 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:-
This invention consists in the production of formic aldehyde vapours from
trioxymethylene or other solid polymeric modifications of formic aldehyde moro
particularly for the purposes of disinfection.
It is already known that pure formic aldehyde vapours can be obtained from
the commercial formic aldehyde solution by means of heating in suitable apparatus
under pressure, preferably in the presence of neutral salts, as for instance calcium
chloride in the solution. This method is described in Specification No. 20773 of
1896.
My foreign correspondents have discovered that this method for the production
of formic aldehyde vapours may be extended to the employment of trioxy-
methylene or other solid polymeric modifications of formic aldehyde in place of the
commercial solution. For this purpose and according to the present invention the
trioxymethylene (or other solid polymer of formic aldehyde) is mixed with water,
to which neutral salts may be added, and heated under pressure. On warming
the trioxymethylene dissolves and as the temperature increases becomes dissociated
and pure formic aldehyde vapours are generated: this dissociation is most complete
at a temperature of about 1300 or 135° C., although it commences to take place at a
lower temperature.
For the purpose of the invention it is preferable to prepare a mixture of
trioxymethylene (or other solid polymer of formic aldehyde) and a neutral salt by 2
preference sea salt in the proportion of about 100 parts of trioxymethylene to
40 parts of sea salt. This mixture is made into the form of cakes or tablets and
this is best effected by moistening it with water and then drying, the amount of
water used and the drying operation being regulated, as will be well understood,
so that the cakes shall be sufficiently porous to readily dissolve in water especially 3
under pressure. The size of the cakes is preferably such that one cake is
sufficient to disinfect a room of from 50 to 100 cubic meters.
The cakes of trioxymethylene and neutral salt thus prepared are well adapted
for transport to a distance and when required for use have only to be placed in
water and heated under pressure.
3
In order to carry out the invention any suitable autoclave capable of with-
standing 5 or 6 atmospheric pressures, such as is employed for the generation of
formic aldehyde vapours from the commercial solution, may be used. As
compared with the latter method of generating formic aldehyde vapours from the
commercial solution, the new method has the advantage that trioxymethylene or 4
other polymers of formic aldehyde being in solid form are much more convenient
for transport and manipulation. It is also possible in this way to generate in an
equal time a much larger quantity of pure formic aldehyde vapours, which is very
desirable in the disinfection of large rooms or buildings where it is always difficult
to secure perfect enclosure.
4

page_text: Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondents and in what
manner the same is to be performed I declare that what I claim is:-
1. The method of producing formic aldehyde vapours which consists in mixing
a solid polymer of formic aldehyde with water and then heating the mixture under
pressure, substantially as set forth.
2. The method of producing formic aldehyde vapours which consists in mixing
a solid polymer of formic aldehyde with water and a neutral salt and then heating
the mixture under pressure substantially as set forth.
5. A material for use in the production of formic aldehyde vapours, said
material consisting of a solid polymer of formic aldehyde and a neutral salt mixed
together and in a concrete form.
Dated this 6th day of September 1897
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, W.C., Chartered Patent Agents.