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Infection and Disinfection: Leave

Meantime have in readiness wet strips of paper and paste, or adhesive plaster, with which to seal up the cracks of the door immediately on leaving the room. When everything is in readiness and the pail containing the permanganate crystals is in place, pour over them the formaldehyde solution. Leave the room and seal up the door on the outside as quickly as possible. The formaldehyde is promptly liberated in great quantities. Hence the necessity that all preparations be made in advance and that the operator leave the room at once on the combination of the two chemicals. Leave the room closed for at least four hours.

Quantities and Proportions.-Care must be taken not to put too much formaldehyde into a single container.

The reaction is violent and there is great effervescence and bubbling. If the rooms are large, as in the case of school rooms, public halls and the like, more than one container should be used.

The following quantities may be used safely in the containers recommended: 10 or 12-quart milk-pail.

Formaldehyde, 16 ounces, Permanganate, 6 ounces. 14-quart milk-pail.

Formaldehyde, 24 ounces.

Permanganate, 10 ounces.

A receptacle of ample capacity, not less than mentioned above, should always be used, as otherwise, the effervescence resulting from the reaction between the two substances may carry the mixture, or some of it, over the sides of the receptacle and stain the carpet or floor. As permanganate of potassium is liable to stain anything with which it comes into contact, use great care in handling it.

Remember that the permanganate must always be put in before the formaldehyde solution. - Conservation of Heat. If the bricks and water which are placed in the tub are cold, it is a good plan to set the tin pail snugly into a wooden or pulp bucket. Or wrap it tightly with several layers of asbestos paper.

This is done to retain within the generator the heat, which is very important to the proper generation of the gas. If the bricks and water are hot this will not be necessary.

Selection of Materials. - The chemicals required for formaldehyde disinfection are not expensive and the best quality should be obtained from a reliable dealer. Secure the highest grade 40 per cent aqueous solution of formaldehyde on the market. An inferior grade may fail to do its work and thus bring about unfortunate results by giving a false sense of security. The fine needle-shaped crystals of potassium permanganate are better than the rhomboid. See that you get this substance in crystals.

Do not accept the dust which often contains impurities. Never use formaldehyde candles. They are not reliable. Do not rely upon advertised apparatus, disinfectants, and processes. Nothing can be better or cheaper than the plan above set forth.

Formaldehyde Solution. -The fairly rapid liberation of gas may be secured by sprinkling 40 per cent formaldehyde solution over sheets hung in the room requiring disinfection and containing the articles to be disinfected. One pint of formaldehyde should be used for every 1,000 cubic feet of air space in the apartment, if there is not too much opportunity for the escape of the gas through cracks, windows, doors, etc. If the gas can find easy escape, proportionately more of the solution must be used. Since by either the permanganate method or by the sheet method, formaldehyde gas is rapidly liberated, it is essential that all preparations be made in advance for the operator to leave the room promptly. The door should be closed and sealed and the room left closed for not less than six hours, after which the door and windows may be opened and the room aired.

The odor of formaldehyde, if it persists so as to be objectionable, can be removed, or at least moderated, by hanging up towels or sheets in the room and sprinkling them with ammonia water.

Cautions. - Formaldehyde is intensely irritating to the eyes, nose and mouth. It kills the upper layers of the skin if applied in too strong solutions. The inhalation in ordinary quantities of such formaldehyde as is given off while sprinkling sheets in a room about to be disinfected, is uncomfortable, but not dangerous. The discomfort may be lessened by tying a moist towel over the mouth and nose while engaged in such work. Injury to the hands can be avoided by greasing them well before they come into contact with the formaldehyde solution, or by wearing rubber gloves.