Improvements in the Production of Vapours of Formic Aldehyde and Apparatus for the same.
Year: 1896

page_text: Date of Application (in United Kingdom), 19th Sept., 1896
Complete Specification Loft 21st June 1807 Accented 31st July 1807
Date of Application (in United Kingdom), 19th Sept., 1896
Complete Specification Left, 21st June, 1807 Accepted, 31st July, 1207
PROVISIONAL SPECIFICATION.
Improvements in the Production of Vapours of Formic Aldehyde and
Apparatus for the same.
I, JEAN JOSEPH AUGUSTE TRILLAT, of 3 Rue Franklin, Paris in the Republic of
France, Chemist, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved process and apparatus for the production
of vapours of formic aldehyde, and is particularly applicable for disinfecting
purposes.
It has for its object an arrangement called a formogenic autoclave, by means of
which the direct and instantaneous transformation of solutions of formic aldehyde
into non-polymerised vapours may be effected without the intervention of a current
of air or of steam or of carbonic acid.
Up to the present time no means have been found of regenerating the vapours of
formic aldehyde from the commercial 40 per cent solution. The most simple
process would evidently be to heat the solution so as to drive off the vapours, but
an insurmountable obstacle is met; polymerisation takes place and the solution
finally is transformed into a solid substance. This explains the want of success up
to the present. The arrangement which is the subject of the present application
constitutes then a novelty in the sense that it allows the integral transformation of
solutions into vapour.
The formogenic autoclave consists in a simple autoclave capable of withstanding
a pressure from 5 to 6 atmospheres and which can be rapidly heated by some
means. It is provided with a safety valve, with a manometer and with an orifice
for the introduction of the solution. On the cover are fixed four escape tubes
controlled by a simple cock. The capacity of the autoclave is variable. In order
to effect the regeneration of formic aldehyde vapour from the commercial solution
the latter is placed in the autoclave and the pressure increased by heating to three
or four atmospheres. At this point and without ceasing to apply heat the pressure
is suddenly relieved by opening the cock which controls the escape tubes. The
aldehydic gas is discharged into the atmosphere in the form of vapour pure and
free from polymerisation products.
If the temperature and pressure are sufficiently high the complete transformation
of the whole of the contents of the autoclave is at once obtained.

page_text: It is possible also by regulating the heat to keep the pressure at say two atmos-
pheres. By this means the regeneration of the aldehydic vapours is prolonged.
The addition of a neutral salt dissolved in the formic aldehyde solution facilitates
the evolution of the vapours.
Dated this 16th day of September 1896.-
C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.
Improvements in the Production of Vapours of Formic Aldehyde and
Apparatus for the same.
I, JEAN JOSEPH AUGUSTE TRILLAT, of 3 Rue Franklin, Paris in the Republic of
France, Chemist, 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 relates to an improved process and apparatus for the production
of vapours of formic aldehyde and is particularly applicable for disinfecting
purposes.
It has for its object an arrangement called a formogenic autoclave, by means of
which the direct transformation of solutions of formic aldehyde into non-
polymerised vapours may be effected without the intervention of a current of air or
of steam or of carbonic acid.
Up to the present time no efficient means have lieen found of regenerating the
vapours of formic aldehyde from the commercial aqueous solution. The most
simple process if practicable would evidently be to heat the solution so as to drive
off the dissolved vapours of formic aldehyde, but an insurmountable obstacle is
met: polymerisation takes place and the solution finally is transformed into a solid
substance. This explains the want of success up to the present. The arrangement
which is the subject of the present application constitutes then a novelty in the
sense that it allows the integral transformation of aqueous solutions into vapour of
formic aldehyde.
The formogenic autoclave consists in a simple autoclave capable of withstanding
a pressure from 5 to 6 atmospheres and which can be rapidly heated by some
means. It is provided with a safety valve, with a pressure gauge and with an
crifice for the introduction of the solution. On the cover are fixed one or more
escape tubes controlled by a simple cock or cocks.
The accompanying drawing represents a central vertical section of an apparatus
or autoclave constructed for the purpose of my invention.
In this drawing 1 is a strong flanged vessel of silver copper or other suitable
metal provided with a strong removable flanged cover 2, preferably of gun metal
or bronze, with india rubber ring packing adapted to be closed hermetically by
means of hinged bolts 3. The vessel rests by means of its flange 4 inside an outer
sheet-metal casing 5 which is supported on feet 6. A rose Bunsen burner 8 serves
to heat the vessel 1, or a petroleum or alcohol lamp that permits of rapid heating
may be employed: the hot gases of combustion pass up between the vessel 1 and the
casing 5, and escape through holes 9. The apparatus is provided with a pressure
gauge 10, a safety valve 10%, a copper thermometer tube casing 11 (in which may
be inserted a thermometer 11 with iron shield casing) and a screw-down stop
valve 12, all mounted on the cover 2. The screw-down valve is fitted with an
outlet pipe 13, to which may be adapted a flexible copper tube 13 of small bore to
allow the discharge of the formic aldehyde vapours into a closed room or compartment

page_text: which is to be disinfected through a small aperture such as the keyhole of the door
thereof, the autoclave itself being referably situated outside the room or com-
partment. The capacity of the autoclave is variable.
In order to effect the regeneration of formic aldehyde vapour from the aqueous
solution the latter is placed in the autoclave and the pressure increased by heating
to three or four atmospheres, the temperature of the interior being then about 130° C.
At this point and without ceasing to apply heat the pressure is relieved by opening
the cock 12 which controls the escape tube 13. The aldehydic gas is discharged
into the atmosphere in the form of vapour pure and free from polymerisation
products.
If the above temperature and pressure are maintained the transformation of
nearly the whole of the formic aldehyde contents of the autoclave into vapour is
obtained.
It is possible also by regulating the heat to keep the pressure at say two atmos-
pheres. By this means the regeneration of the aldehydic vapours is prolonged and
less complete. An essential feature of this invention is that the heating should be
effected under considerable pressure. It is important to add a neutral salt such
as calcium chloride for example dissolved in the formic aldehyde solution and pre-
ferably to saturation to facilitate the evolution of the vapours
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:-
The mode or process and apparatus hereinbefore described whereby vapours of
formic aldehyde are produced without polymerisation by heating aqueous formic
aldehyde solution, preferably with a neutral salt, in a closed vessel under a pressure
of preferably 3 or 4 atmospheres and then discharging the compressed vapours from
the said vessel through an outlet or outlets substantially as set forth.
Dated the 21st day of June 1897.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, W.C., Chartered Patent Agents.