This is probably the most effective in destroying noxious effluvia and putrid odours, and in checking the spread of contagious diseases. But as the gas itself is deleterious, except in a very diluted state, it must he used with caution in occupied appartments. To disinfect rooms from which the occupants have been removed, mix common salt and black oxide of manganese in equal quantities. Mix also in an earthen basin equal weights of oil of vitriol and water, and when it has cooled put it into a bottle for use. Into a china or earthen basin put from 1 to 3 oz. of the powder, according to the size of the room, and pour over it twice or thrice as much of the mixed acid. Place it in the apartment, and close the doors and windows for a few hours; the doors and windows are then thrown open till the smell of chlorine disappears. Dr. A. T. Thomson directs a mixture of 1 oz. of salt and 1/2 oz. of black oxide of manganese to be put into a china cup, and 6 fluid drs. of oil of vitriol poured on it, the cup being placed in a pipkin of hot sand. Instead of the above ingredients, some chloride of lime may be placed in a large jar or basin, and a mixture of acetic acid and water poured on it. When used in, or near the apartments of the sick, great care must be taken that the chlorine is so diluted with air that it shall occasion no annoyance to the invalid. Some contrivances have been adopted to render the extrication of chlorine gradual and continual. Smith's Chlorine Fumigator, and the more simple one of Messrs. Heathfield & Burgess, are very convenient. Another method is proposed by Mr. Scanan, in the ' Pharmaceutical Journal,' vol. vii, page 343. By such contrivances, chlorine may with care be safely employed in houses occupied by the sick (in the passages, stairs, &c), to prevent the spread of infectious fevers: but chloride of lime, simply mixed with water, in the proportion of not more than 1 oz. to a quart, is usually sufficient to purify the chamber of the sick. It should be occasionally sprinkled on the floor, and also placed about the room in shallow dishes, or a linen cloth moistened with it, suspended on a line. The same method may be pursued in all places where unpleasant smells prevail. Iodine. A little placed on a plate, diffuses into the atmosphere of a sick room, and is a useful disinfectant, Nitric Fumigation. Put into a china cup equal measures of sulphuric acid and water, and add to it, from time to time, small quantities of powdered nitre: or put 2 or 3 drs. of powdered nitre into a cup, and pour over it about an equal quantity of oil of vitriol. Stir it with a piece of glass, or tobacco-pipe, and remove it from time to time to different parts of the apartment. For large rooms 2 or 3 cups may be required. It is often recommended to apply heat; but Dr. Bateman, of the Fever Hospital, found this unnecessary and objectionable, especially in the apartments of the sick. No metallic or wooden stirrers, or vessels, must be used.