The use of chlorine and sulphurous gases is objectionable because of their irritating quali ties. Sulphur fumes to be effective must be accompanied by moisture. Steam from a boiling kettle will do. A more modern disinfectant is formaldehyde, made by subjecting methyl alcohol to oxidation and commonly known in commerce as formalin, which is a 40-per cent solution of formaldehyde. It is readily soluble in water, does not destroy clothing or furniture and is virtually non-poisonous. It is used for disinfecting surgical instruments, for the wash ing out of sinuses and of indolent and foul ulcers and for the disinfection of dwelling rooms. An approved method of using it for the last-named purpose is to pour 10 ounces of for malin upon 4 ounces of potassium permanganate. This should be done in a sufficiently large vessel to obviate spattering, and the vessel should be set upon a brick or stone base. To be effective the temperature of the room must not be less than 65 and a humidity of 65 degrees is desir able. This moisture may be provided by boiling a tea-kettle in the room for a time before the gas is liberated, and this will serve also to warm up the room. The proportions given are for a space of 1,000 cubic feet. Larger rooms will require more formalin. Another method which is highly recommended is the following: Make a mixture of three parts of 40-per cent formalin and one part of carbolic acid. Eight ounces of this mixture will be required for each 1,000 cubic feet of space and the room must remain closed for 12 hours. A sufficient number of sheets are saturated with the mixture, each sheet holding about six ounces, and they are hung on lines strung across the room, free of the walls and floor. A so-called ((solids form of formal dehyde has been placed on the market, with a container in which it is burned. If sufficient formaldehyde is used for the size of the room this device is convenient and effective, as the resulting gas quickly penetrates all cracks and crevices and renders the air clean and pure, be sides destroying all infectious germs.
Most of the metallic and acid disinfectants are more or less objectionable on account of their destructive action to the skin and tissues. Osmic acid, bromine and iodine are useful in their respective places. The relative disinfectant values of the various germicides in common use, based on the efficiency of carbolic acid on the typhoid germ as 1, is as follows : Corrosive sublimate 400-3.340 Ii Iodine water 146-220 100 Iodine trichloride 94 Bromine water 64 um permangana 42 Chlorine water te 28 Silver nitrate 15 Formic acid Benzoic acid 5.0 Sodium bisulphate 4.1 Cresylic acid 3.7 Copper sulphate 2.0 Lactic acid 1.8 Bucalyptol 1.2 In all cases of infectious or contagious diseases disinfection should be complete; arti cles infected should be burned, boiled or disin fected and not buried or thrown into sewers before being treated with a proper disinfecting agent, for infecting germs have been known to lie dormant for years. In disinfecting a room in which infectious disease has been housed a thorough mechanical cleansing should be car ried out after a preliminary disinfecting. The walls should be carefully brushed with a vacuum cleaner and the floors and woodwork scrubbed with hot water and soap, finishing with a f or malin solution to which has been added a little glycerine. A fresh coat of paint or varnish on the woodwork and new wall-paper or calcimine placed on the walls complete the list of essen tial precautions. The ceiling may be regarded as safe. (See also the article DisiNFEcriorr). Consult Christian, M., (Disinfection and Disin fectants) (London 1913) ; Rosenau, M. J., (Dis infection and Disin fectants ) ( Philadelphia 1902).