104 Solid Matters in Expired Air. A rough calculation was given of the total quantity of organic matter exhaled from the lungs in twenty-four hours. In the case of an adult it amounted to about forty-six grains. In kidney diseases a very large amount of organic matter was thrown off from the lungs. In a case of diphtheria confervoid filaments were observed; and in two other cases-one of measles, the other of hooping cough numerous specimens of a small celled torula were detected. The results of Dr. Ransome's experiments throw no light on the subject of the germ theory of disease. They show, however, the readiness with which the matters thrown out from the lungs support fermentation, and they afford a further illustration of the dangers arising from the ill-ventilation of hospitals. Dundas Thompson and Cainey found' sporules, confervoid fungi, vibriones, hairs, &c., in the wards of St. Thomas' Hospital, London, devoted to cholera patients. Pouchet has recorded (Comptes Rendus, Tome 48) the results of more than a thousand examinations of the solid matters floating in the atmosphere. He found therein, besides various kinds of mineral matter, species of vibriones, oxyuris, naviculæ, bacilaria, and diatoms; also epithelial scales, parts of insects, and various kinds of the debris of organized bodies. Pouchet's experiments were repeated and with like results by M. M. Joly and Muset (Comptes Rendus for 1860, page 647). Eiselt, Reviel, Devergie, Balbiani, Silvestri, Selmi, Robin Cohn, Beall, Samuelson, Wright, Douglas, Cunningham, Darcer, Sigerson, Sund, Angus Smith, DeChaumont, and Hogg have each of them published papers on the presence of organized structures in the atmosphere. Report of the Committee for scientific enquiries in relation to the Cholera Epidemic of 1854. Amount of Air for each Person. 105 CHAPTER XI. VENTILATION AND HEATING OF DWELLINGS. An average sized man inspires about 16 cubic feet of air. Before inspiration this air usually contains from 04 to 05 per cent. of carbonic acid; after expiration from 4 to 5 per cent. of carbonic acid. It is not, therefore, merely necessary to supply a man with the actual quantity of air which he requires for inhalation, but with a quantity of pure air sufficient to reduce the percentage of carbonic acid in the gases expired from 4 to 04 or 05. The amount of air necessary for this purpose, as well as that sufficient to prevent a candle from vitiating the atmosphere, are shown in the following table extracted from Dr. Angus Smith's work, "Air and Rain," page 522: AMOUNT OF PURE AIR REQUIRED per Hour, in CUBIC FEET. Air re-breathed cannot apparently be made to take up more than 10 per cent. of carbonic acid, simply because animals cannot continue to breathe at all when the gas attains to that proportion. When air contains 3 per cent. of carbonic acid, lighted candles go out, and animals speedily die. The fatal effect of carbonic acid is due to the fact that it prevents expulsion of carbonic acid gas from the venous blood, which, consequently, rapidly accumulates and exercises a poisonous action. Regnault and Reiset have shown that in an atmosphere containing 40 per cent. of oxygen, instead of its usual proportion, animals can exist for hours, even when the proportion of carbonic acid is so high as 23 per cent. H 106 Amount of Air for each Person. The sick require more air than healthy persons. In diseases of an inflammatory character there is an abundant exhalation of organic matter, which, unless speedily oxidized, renders the atmosphere intolerable. A less supply than 3,500 cubic feet per hour is insufficient for a sick adult or even child. Gangrene, pyæmia, small-pox, erysipelas, and fevers taint the air to an extraordinary extent; and persons suffering from those diseases should be supplied with from 5,000 to 7,000 cubic feet per hour. In typhus and pyæmia almost complete exposure to the open air has been attended with the most favourable results. It is now generally acknowledged that persons suffering from consumption are much benefited by remaining in the open air during the whole day, unless the weather be unfavourable. General Morin, in a report to the French Government in 1860, gives the statements shown in the diagram :— CUBIC FEET OF AIR REQUIRED PER HEAD, PER HOUR, IN TEMPERATE In British barracks the regulation allowance of air is 1,000 cubic feet per hour. The space allowed to each soldier in sleeping and other apartments is fixed by the military authorities at 600 cubic feet in permanent barracks; 400 in huts; 600 in wooden and 1,200 in permanent hospitals at home, and 1,500 in the tropics. According to the poor law regulations, each person is allowed 300 cubic feet to sleep in; 500 if sick. A room 10 feet high, 15 feet long, and 10 feet wide contains 1,500 cubic feet of air, and may, according to the Dublin Sanitary regulations, accommodate five persons. The atmosphere of the largest room in which persons are living becomes bad, unless there are apertures of sufficient magnitude to admit fresh air and to allow the foul air to escape. In a sleeping apartment there should be an opening of 24 square inches to admit the fresh air required for one individual-adult or child. The inlet aperture should be lower than the outlet one, and one of equal size to allow of the egress of vitiated air. M'Kinnell's and Arnott's Ventilators. 107 The diagram shows the comparative size of a man and that of The cube shows the quan tity of air which every hour passes into the lungs of one person, averaging both sexes and all ages. The outlets for the vitiated air should, as a rule, be removed as far as possible from the inlets for the pure air; otherwise the circulation of the air throughout the apartment will not be perfect. In M'Kinnell's ventilator, however, the inlet and outlet are close together. This ventilator is intended to introduce the pure air through the ceiling. It consists of two tubes, one placed within the other. The inner is a little longer than the outer one, and through it the vitiated air escapes. The outer tube is that through which the pure air descends into the room; and the lower part of it being provided with a flange, the air at first spreads along the ceiling, and afterwards descends by the walls to the lowest part of the room. Arnott's ventilator is simply an opening, provided with a valve, leading into the chimney. It is most useful for the purpose, but occasionally smoke from the chimney forces a passage through it into the room. The air thrown off from the body and the gaseous products of combustion are light, and ascend; therefore the vitiated air should pass out at the highest point of the apartment. The purer and heavier air should be admitted about eight feet above the floor. If the apartment is ventilated by heated air, then the openings for its admission may be at or near the floor; but cold air flowing into a room at the lowest point occasions much discomfort, by cooling the feet, and in other ways. The air may be warmed by passing it through boxes heated by coils of pipes, through which a current of steam or of hot M'KINNELL'S PATENT water flows; but under no circumstances should air from a furnace be 108 Rules for Ventilation. admitted into rooms. An economical method of introducing pure, warm air into a room is to construct the open fireplace or stove flue in such a way that the air heated by the outer surface may pass into the room. This system of simultaneously heating and ventilating apartments has been found very successful in many hospital wards and barrack-rooms. The Sherringham valve is an excellent contrivance for admitting fresh air without occasioning a draught, unless when a very strong wind blows upon it. It can be used either as outlet or inlet, by fixing the hinged valve in the necessary position, and the valve can, if necessary, be closed by a balanced weight. This valve is generally placed in the upper part of the wall, and it is usually 9 inches by 3, with an area of 27 square inches. SHERRINGHAM VENTILATOR. Dr. DeChaumont in his excellent pamphlet on ventilation states: 1. We cannot safely accept a lower standard than 06 per cent. of carbonic acid. 2. We cannot safely legislate for anything short of uniform diffusion in an air space. 3. Uniform diffusion being supposed, we cannot preserve our minimum standard of purity with a less delivery of fresh air than 3,000 cubic feet per head per hour. 4. We cannot safely change the air on an average oftener than six times in an hour without producing draughts. 5. With ordinary means of ventilation, we can seldom hope to succeed in changing the air even six times in an hour. 6. We must provide an air space which will admit of the delivery of 3,000 cubic feet per head, per hour, and at the same time preclude the necessity of changing the whole air so often as six times per hour. 7. To fulfil all the above conditions, a minimum of 1,000 cubic feet per head is absolutely necessary. 8. To provide the supply of 3,000 cubic feet per head per hour, so that the velocity of the current at the point of entry should not exceed 5 feet per second, 48 square inches of total inlet and outlet area ought to be provided, and this independent of the chimney, if there be an open fireplace. Where gas is burned, it is desirable to have an opening in the ceiling exactly over the gas-lights, and a tin tube leading from it direct to the open air. The cost of the tube (which is placed between the ceiling of the room to be ventilated and the floor of the one above it) is trifling. When the tube is passed into the air, it should not be carried up too high, otherwise down-draughts might be produced. Perforated bricks are now very generally placed in the walls of houses. Iron frames covered with perforated zinc are good substitutes for the porous bricks; when provided with valves -to close them if necessary-they are very good ventilators. Louch's ventilator consists of a wooden box, containing three or four partitions of perforated zinc. The box is inserted obliquely in the wall near the ceiling, and the air passing through it is |