US737413A - Formaldehyde-generator. - Google Patents

Description

No. 737,413. PATENTED AUG.I25, 1903. R. W. JOHNSON.

FRMALDEHYDE GENERATOR.

APPLIOATION FILED DB0. 6. 1901.

No MODEL.

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UNTTED STATES Patented August 25, 1903.

PATENT OFFICE.

FORMALDEHYDE-G EN ERATOR.

SPECIFICATION forming part of Letters Patent No. 737,413, dated August 25, 1903.

Application led December 6, 1901. Serial No. 84,908. (No model.)

To all whom, t may concern:

Be it known that l, ROBERT W. JOHNSON, a citizen of the United States, residing in the city of New Brunswick, county of Middlesex, State of New Jersey, have invented a certain new and useful Improvement in Formaldehyde-Generators, of which the following is a description.

The object I have in view is to produce aV simple and eifective device for producing formaldehyde gas from the solid or polymerized forms of formaldehyde, commercially known as paraform, by combustion in a container in which the combustion is restricted and the gas is driven oft by the heat produced by burning a small portion of the solid.

This device is illustrated in the drawings,

former to give the desired thickness, the.

layers being cemented together by silicate of soda. In this way there is produced a rectangular tube of the proper length. The top of the container is closed by a capl B, made of a square of perforated sheet metal of such size that when the corners b of the sheet are turned down on the dotted lines shown in in Fig. 3 the square of smaller size within these dotted lines will be that of the side walls of the container. This cap is preferably secured to the container by wrapping the points b between layers of the asbestos paper of which the side walls A are formed, and the cap may be additionally fixed in position by means of the silicate of soda. The mass of paraform is compressed into the form of a cylindrical candle C, which is preferably coated with paraffin to prevent evaporation before use. This candle has a length somewhat less than the side walls of the container, and its diameter is equal to the width of these side walls, at least at its larger end, Fig. 2, so as to touch such side walls and be held in a central position by them. The can; dle is inserted into the container from the bottom until it rests against the under side of the cap B. The candle, although touching the side walls of the container, does not en tirely fill the container, because of its cylindrical form, the angular container providing draft-openings at the angles for permitting combustion of the candle at its lower end and for directing the products of combustion upwardly in contact with the sides of the candle. The candle is held in the container by a bridge-piece D, formed, preferably, of a strip of perforated metal having a less width than the container and inserted into the container from the bottom and secured therein .by the silicate-of-soda cement and also by punching the metal into the asbestos walls by means of a suitable tool, as shown at d. This bridge-piece holds the candle firmly in position, so that it will not be injured by shipment, and also forms a support for the candle while burning, preventing it from dropping to the lower end of the container. The lower end of the container has V-shaped openings a cut into two of the side walls, so as to form air-inlets for supporting combustion atthe lower end of the candle.

In use the candle is lighted at its lower end, and the generator is then placed in a shallow dish containing water, which, however,should not have a depth sufficient to entirely close the air-inlets a. The candle burns at its lower end, to which the combustion is restricted by the restriction ot' the outlet at the top ofthe container, the formaldehyde gas produced by the volatilization of the paraform escaping through the perforated cap into the room or space to be fnmigated or disinfected. The water in the dish in which the generator is placed is absorbed by the asbestos-paper side walls and is drawn by capillary attraction into the heated zone around the flame at the lower end of the candle, where it is vaporized and -passing upwardly both inside and outside of the container mingles with the formaldehyde gas and prevents the repolymerization-of the formaldehyde. 1

The asbestos forming the side walls of the container being an effective non-conductor of heat conserves the heat produced by the llame at the lower end of the candle and restilts inthe conversion of the paraform into formaldehyde gas with the minimum loss by combustion. The use of asbestos paper also for the side walls of the container reduces the expense of the construction over what it would be if metal were employed. The metal parts are simple and inexpensive. The rectangular form of the container is also advantageous, because of the saving of space in packing.

l. In aformaldehyde-generator,a container made in the form of a tube of angular crosssection open at one end andy closed at the other end by a perforated cap, in combination with a candle of cylindrical form touching the side Walls of the container and held against lateral displacement thereby but leaving draft-openings at the angles of the container, substantially as set forth.

2. In a'formaldehyde-generator,a container made in the form of a tube of angular crosssection open at one end and closed at the other end by a perforated cap, and a bridge-piece connecting the walls of the container near its open end, in combination with a candle of cylindrical form touching the side walls of the container but leaving draft-openings at the angles of the container, said candle extending lengthwise of the container from the cap to the bridge-piece, substantially as set forth.

3. In a formaldehyde-generator, the conrainer made as a tube of two or more thicknesses of asbestos paper cemented together and provided with a perforated cap at one end and with an interior support for the candle near the other end, substantially as set forth.

4. In a formaldehyde-generator, the con- 4o tainer made of two or more thicknesses of asbestes paper cemented together, and closed at one end by a cap of perforated sheet metal having points turned at right angles to the body of the cap and secured between the layers of the asbestos paper, substantially as set forth.

5. In a formaldehyde-generator, -the container made in tubular form of asbestos paper and provided with a perforated cap at 5o one end and with a metal bridge-piece connecting the walls of the container near-the other end and secured thereto, substantially as set forth.

6. A formaldehyde-generator having the asbestos side Walls A provided with air-open ings a, the .perforated metal cap B, and thc metal bridge-piece, D, substantially as set forth.

This specification signed and witnessed this 6o 3d day of December, 1901.

ROBERT W. JOHNSON.

Vitnesses:

EDWARD MORRIS, JNO. L. CARBERRY.

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