Bichloride of Mercury (corrosive sublimate) is a potent poison and a powerful germicide; in solutions of 1:15,000 it stops decomposition; in solutions of 1:2,000 it kills bacteria in two hours; and in a strength of 1:500 it acts very quickly as a germicide for all bacteria, and even for spores. Corrosive sublimate dissolves in sixteen parts of cold and three parts of boiling water, but for disinfecting purposes it should be colored so that it may not be inadvertently used for other purposes, as the normal solutions are colorless and may accidentally be used internally. The action of the bichloride is increased by heat.

Formalin is a forty per cent solution of formaldehyde gas, and its uses and methods of employment have already been considered.

Potassium Permanganate is a good germicide, and weak solutions of it are sufficient to kill some bacteria, but the objections against its use are that solutions of potassium permanganate become inert and decompose on coming in contact with any organic matter. Furthermore, the chemical would be too expensive for disinfecting purposes.

Ferrous Sulphate (copperas) was formerly very extensively used for disinfecting purposes, but is not so used at present, owing to the fact that it has been learned that the germicidal power of this material is very slight, and that its value depends mostly upon its deodorizing power, for which reason it is used on excreta in privy vaults, etc.

Lime.—When carbonate of lime is calcined the product is common lime, which, upon being mixed with water, produces slaked lime; when to the latter considerable water is added, the product is milk of lime, and also whitewash. Whitewash is often used to disinfect walls and ceilings of cellars as well as of rooms; milk of lime is used to disinfect excreta in privy vaults, school sinks, etc. Whenever lime is used for disinfecting excreta it should be used generously, and be thoroughly mixed with the material to be disinfected.

Disinfection of Rooms

Practical disinfection is not a routine, uniform, and thoughtless process, but demands the detailed, conscientious application of scientific data gained by research and laboratory experiments. Disinfection to be thorough and successful cannot be applied to all objects, material, and diseases in like manner, but must be adjusted to the needs of every case, and must be performed conscientiously. Placing a sulphur candle in a room, spilling a quart of carbolic acid or a couple of pounds of chlorinated lime upon the floors or objects, may be regarded as disinfection by laymen, but in municipal disinfection the disinfector must be thoroughly versed in the science of disinfection and be prepared to apply its dictates to practice.

Rooms.—In the disinfection of rooms the disinfectant used varies with the part of the room as well as with the character of the room. When a gaseous disinfectant is to be used sulphur dioxide or formaldehyde is employed, with the tendency lately to replace the former by the latter. Wherever there are delicate furnishings, tapestries, etc., sulphur cannot be used on account of its destructive character; when sulphur is employed it is, as a rule, in the poorer class of tenement houses where there is very little of value to be injured by the gas, and where the sulphur is of additional value as an insecticide. Whenever gaseous disinfectants are used the principal work of the disinfector is in the closing up of the cracks, apertures, holes, and all openings from the room to the outer air, as otherwise the gaseous disinfectant will escape. The closing up of the open spaces is accomplished usually by means of gummed-paper strips, which are obtainable in rolls and need only to be moistened and applied to the cracks, etc. Openings into chimneys, ventilators, transoms, and the like must not be overlooked by the disinfector. After the openings have already been closed up the disinfectant is applied and the disinfector quickly leaves the room, being careful to close the door behind him and to paste gummed paper over the door cracks. The room must be left closed for at least twelve, or better, for twenty-four hours, when it should be opened and well aired.

Walls and Ceilings of rooms should be disinfected by scrubbing with a solution of corrosive sublimate or carbolic acid; and in cases of tuberculosis and wherever there is fear of infection adhering to the walls and ceilings, all paper, kalsomine, or paint should be scraped off and new paper, kalsomine, or paint applied.

Metal Furniture should first be scrubbed and washed with hot soapsuds, and then a solution of formalin, carbolic acid, or bichloride applied to the surfaces and cracks.

Wooden Bedsteads should be washed with a disinfecting solution and subjected to a gaseous disinfectant in order that all cracks and openings be penetrated and all insects be destroyed.

Bedding, Mattresses, Pillows, Quilts, etc., should be packed in clean sheets moistened with a five per cent solution of formalin, and then carted away to be thoroughly disinfected by steam in a special apparatus.

Sheets, Small Linen and Cotton Objects, Tablecloths, etc., should be soaked in a carbolic-acid solution and then boiled.

Rubbish, Rags, and Objects of Little Value found in an infected room are best burned.

Glassware and Chinaware should either be boiled or subjected to dry heat.

Carpets should first be subjected to a gaseous disinfectant, and then be wrapped in sheets wetted with formalin solution and sent to be steamed. Spots and stains in carpets should be thoroughly washed before being steamed, as the latter fixes the stains.

Woolen Goods and Wool are injured by being steamed, and hence may be best disinfected by formalin solutions or by formaldehyde gas.

Books are very difficult to disinfect, especially such books as were handled by the patient, on account of the difficulty of getting the disinfectant to act on every page of the book. The only way to disinfect books is to hang them up so that the leaves are all open, and then to subject them to the action of formaldehyde gas for twelve hours. Another method sometimes employed is to sprinkle a five per cent solution of formalin on every other page of the book; but this is rather a slow process.[21]

Stables need careful and thorough disinfection. All manure, hay, feed, etc., should be collected, soaked in oil, and burned. The walls, ceilings, and floors should then be washed with a strong disinfecting solution applied with a hose; all cracks are to be carefully cleaned and washed. The solution to be used is preferably lysol, creolin, or carbolic acid. After this the whole premises should be fumigated with sulphur or formaldehyde, and then the stable left open for a week to be aired and dried, after which all surfaces should be freshly and thickly kalsomined.

Food cannot be very well disinfected unless it can be subjected to boiling. When this is impossible it should be burned.

Cadavers of infected persons ought to be cremated, but as this is not always practicable, the next best way is to properly wash the surface of the body with a formalin or other disinfecting solution, and then to have the body embalmed, thus disinfecting it internally and externally.

Disinfectors, coming often as they do in contact with infected materials and persons, should know how to disinfect their own persons and clothing. So far as clothing is concerned the rule should be that those handling infected materials have a special uniform[22] which is cleaned and disinfected after the day's work is done. The hands should receive careful attention, as otherwise the disinfector may carry infection to his home. The best method of disinfecting the hands is to thoroughly wash and scrub them for five minutes with green soap, brush, and water, then immerse first for one minute in alcohol, and then in a hot 1:1,000 bichloride solution. The nails should be carefully scrubbed and cleaned.

FOOTNOTES:

[20] Blankets, carpets, and rugs should be frequently hung out on the line in the bright sunlight.—EDITOR.

[21] Unless books are valuable it is best to burn them. Paper will hold germs for several weeks. Recent experiments show that certain pathogenic bacteria, including the bacilli of diphtheria, will live for twenty-eight days on paper money.—EDITOR.

[22] Duck, linen, or any washable material will do.—EDITOR.



CHAPTER XI

Cost of Conveyed Heating Systems[23]

In our variable climate, with its sudden and extreme changes in temperature, the matter of heating and ventilation demands the serious attention of all houseowners and housebuilders.

The most common method of heating the modern dwelling is by a hot-air furnace in the cellar, with sheet-metal ducts for conveying the heated air to the various rooms. The advantages of a furnace are cheapness of installation and, in moderate weather, a plentiful supply of warm but very dry air. The disadvantages are the cost of fuel consumed, the liability of the furnace to give off gas under certain conditions, and the inability to heat certain rooms with some combinations of temperature and wind. The cost of installing a furnace and its proper ducts in a ten-room house is from $250 to $350; such a furnace will consume fifteen to twenty tons of anthracite coal in a season in the latitude of New York City. The hot-air system works better with compact square houses than with long, "rangy" structures. For a house fully exposed to the northwest blasts, one of the other systems should be considered.

Perhaps the next most popular arrangement is a sectional cast-iron hot-water heater, with a system of piping to and from radiators in the rooms to be heated. Hot-water heating has many advantages, some of which are the warmth of the radiators almost as soon as the fire is started and after the fire is out; the moderation of the heat; the freedom from sudden changes in amount of heat radiated; the absence of noise in operation, and the low cost in fuel consumed. Some of the disadvantages are the high cost of installation and the lack of easy or ready control (as the hot water cools slowly, and shutting the radiator valves often puts the whole system out of adjustment). A hot-water heating plant for a ten-room house will cost $400 to $600, according to the type of boiler; the corresponding fuel consumption will be twelve to sixteen tons of coal per season.

The third system in common use is by steam through radiators or coils of pipe connected to a cast-iron sectional boiler, or a steel tubular boiler set in brickwork. This system is in use in practically all large buildings; and its advantages are the moderate cost of installation (as the single-pipe system is very efficient and the pressure to be provided against in connections and fittings is slight); the ease of control (since any good equipment will furnish steam in twenty minutes from the time the fire is started, and fresh coal thrown upon the fire with a closing of dampers will stop the steam supply in five minutes—or any radiator may be turned on or off in an instant); the ability to heat the entire house in any weather, or any single room or suite of rooms only; and, lastly, the moderate fuel consumption.

The disadvantages of steam heat are no heat, or next to none, without the production of steam, involving some noise in operation, and danger of explosion. Steam equipment in a ten-room house will cost $300 to $550, the lower price being for a sectional boiler and the higher for a steel boiler set in brickwork. The fuel consumed will be from ten to fifteen tons per season.

Both hot-water and steam systems require supplementary means of ventilation. Placing the radiators in exposed places, as beneath windows, in the main hall near the front door, in northwest corners and near outside walls, will insure some circulation of air; and, if one or two open fire places be provided on each floor, there will be, in most cases, sufficient ventilation without the use of special ducts.

FOOTNOTES:

[23] See Chapter III for full discussion.—EDITOR.



TRANSCRIBER'S NOTE. =================== 1) Figure numbers (which aren't contiguous) have been preserved. 2) Part III, Chapter V. The table showing thickness of vitrified pipes reads: 4 inches diameter 1/2 inch thick 6 " " 1/16 " " 8 " " 3/4 " " 12 " " 1 " " The thickness figure for the 6 inch pipe has been left as originally printed, but probably is incorrect (logically it should be somewhere between 1/2 inch and 3/4 inch thick).

THE END