so as to receive the influence of the gas; the bed linen, and all woollen garments, being exposed by being spread out on chairs, lines, &c.; the drawers and cupboards opened; and whilst the disinfecting is in actual operation, the windows and doors should be kept shut, to prevent the dissipation of the chlorine. It is found that two ounces of manganese, with a proportionate quantity of the other materials, is sufficient for a room twenty feet wide, forty feet long, and twelve feet high, which contains 20 × 40 × 12 = 9600 cubic feet. It may be mentioned, that breathing chlorine in this highly diluted state is decidedly the reverse of injurious to the general health; although, in a concentrated form, or even unless very much diluted with air, it is irritating in the highest degree; but so very innoxious is it in the very dilute state, that it is occasionally prescribed for the inhalation of consumptive patients. For the satisfaction of those who rely on the authority of a great name, it may be stated, that chlorine used in the manner here recommended was employed, with complete success, by one of the most illustrious of our English chemists, in the case of the Millbank Penitentiary, when a violent and fatal disease broke out there. The operator in this case was FARADAY, than whom there can be no higher authority. It may occasionally be found more convenient to use another mixture for the liberation of chlorine gas, in which case the following may be employed:—One part of manganese is to be drenched with four parts, by weight, of muriatic acid (the spirits of salts of the shops), mixed with one part of water. The gas is evolved slowly in the cold, and rapidly if assisted by a gentle heat. This process is rather more expensive, and possesses no advantage over the one previously described. XI. FERMENTING AND DISTILLING. In ordinary language, the term fermentation is employed to signify the peculiar changes which take place when a solution of sugar, or any vegetable substance containing saccharine matter, is converted into spirit—this, however, is only one of many such kinds of action, which are well known to chemists. The most important fermentations are the saccharine fermentation, when sugar is formed by a change taking place in starch: the vinous, when spirit is formed from sugar; and the acetous, in which vinegar or acetic acid is formed from spirit.