DISINFECT′ANT

An agent which absorbs, neutralises, or destroys, putrescent effluvia, miasmata, or specific contagia, and thus removes the causes of infection. The principal disinfectants are chlorine, iodine, bromine, the so-called chlorides of lime and soda, chloride of zinc, ozone, carbolic acid, the alkaline manganates and permanganates, peat charcoal, the fumes of nitric and nitrous acid, sulphurous acids, heat, and ventilation. The last two are the most efficient and easily applied. The clothing, bedding, ., of patients labouring under contagious diseases may be effectually (?) disinfected by exposure to a temperature a little higher than that of boiling water, for about an hour. Neither the texture nor colour of textile fabrics is injured by a heat of even 250° Fahr. (Dr Henry.) See Disinfecting Chambers . It is a practice at some of the workhouses to bake the clothes of the paupers who have the itch, or who are infested with vermin. The soaking and boiling of clothes in the absence of being able to bake them is by no means a bad method for disinfecting them. The proce is rendered the more effective by adding to the water in which they are immersed or boiled 1 part of strong solution of chloride of lime to 20 or 30 parts of water; or carbolic acid in the proportion of 1 part of the pure acid to 100 parts of water. In the German army, if the clothes cannot be baked they are soaked for 24 hours in water containing 1 part of sulphate of zinc to 120 of water, or 1 part of chloride of zinc to 240 of water, after which they are washed in soap and water and dried. Quicklime rapidly absorbs carbonic acid, sulphuretted hydrogen, and several other noxious gases, and is therefore commonly used as a wash for the walls of buildings. Acetic acid, camphor, fragrant pastilles, cascarilla, brown paper, and other similar substances, are frequently burnt or volatilised by heat, for the purpose of disguising unpleasant odours, but are of little value as disinfectants. The sulphates of iron and zinc have the property of rapidly destroying noxious effluvia. A quantity of either of these sulphates thrown into a ce pool, for instance, will in a few hours render the matter therein quite scentle . Of gaseous disinfectants, “sulphurous acid gas (obtained by burning sulphur) is preferable, on theoretical grounds, to chlorine. No agent checks so effectually the first development of animal and vegetable life. All animal odours and emanations are immediately and most effectually destroyed by it.” (Graham.) See Antiseptic , Deodoriser , Fumigation , Infection , Ozone , Carbolic acid , Salicylic acid , Bacteria as originators of disease, Lime , Chloride , Charcoal , also the Disinfecting Compounds given below . Dr Wynter Blyth divides disinfectants into two great cla es:—Gaseous, and solid or liquid. I. Volatile, in the form of Gas or Vapour. 1. Substances which, like the halogens, appear to form substitution compounds, e.g. Chlorine, Bromine, Iodine. 2. Substances which probably combine chemically, and thus destroy contagion: Sulphurous acid, Nitrous acid, Fumes of other acids. 3. Oxidising substances, such as— Pure air, Oxygen, Ozone. 4. The volatile oils, . Feeble disinfectants, supposed, however, to oxidise— Camphor, Oil of hops, Oil of rue, Oil of rosemary, Oil of chamomile. II. Solid or Liquid Disinfectants. 1. The chlorides of different metals, earths, or bases: Chlorides of the alkalies, Chlorides of iron, Chlorides of copper, Chlorides of manganese, Chlorides of zinc, Chlorides of aluminium, Chlorides of lime, Chlorides of mercury, and, in fact, all chlorides which are soluble. 2. All soluble sulphates, especially sulphates of iron and aluminium. 3. All soluble sulphites. 4. Some acetates, as acetate of iron. 5. Some nitrates, such as the nitrates of potash and soda. 6. Certain agents which appear to arrest putrefaction or condense certain gases, ., without either destruction or oxidation: Carbolic acid, Tar acids, Charcoal, Great cold, Heat sufficient to dry organic substances, but not to char them. 7. Preservative liquids and solutions. Many of these act by coagulating the albumen of organised bodies: Antiseptics, Alcohol, Solutions of corrosive sublimate, Solutions of common salt, Solutions of saltpetre. 8. Destructive agents. Not true disinfectants, they act not by disinfection, but by destruction: A dry heat of 200° to 400° F., The strong undiluted acids and alkalies. 9. Agents which act in many ways, partly by condensing gases, partly by absorbing moisture, and partly by a peculiar action on organic matter analogous to tannin: Dry earths, Clays, The natural and artificial compounds of aluminium. The table on the next page is a summary by the late Dr Letheby of some experiments made by Drs Doug all and Calvert, with the view of determining the relative powers po e ed by certain substances of arresting putrefaction, as measured by their action in preventing the germination of animalcules and fungi, and the development of vaccine lymph. [258] [258] ‘On the Relative Power of various Substances in Preventing the Germination of Animalculæ,’ by John Doug all, 1871. Calvert, ‘Proceedings of the Royal Society,’ vol. xx, p. 185.