The Home Medical Library Volume V Part 20

The main disadvantages of sulphur dioxide as a disinfectant are: (1) that it weakens textile fabrics; (2) blackens and bleaches all vegetable coloring matter; (3) tarnishes metal; and (4) is very injurious and dangerous to those handling it.

There are several methods of employing sulphur in the disinfection of rooms and objects, e. g., the pot, candle, liquid, and furnace methods.

In the pot methods crude sulphur, preferably ground, is used; it is placed in an iron pot and ignited by the aid of alcohol, and in the burning evolves the sulphur dioxide gas. About five pounds of sulphur are to be used for every 1,000 cubic feet of s.p.a.ce. As moisture plays a very important part in developing the disinfecting properties of sulphur dioxide, the anhydrous gas being inactive as a disinfectant, it is advisable to place the pot in a large pan filled with water, so that the evaporated water may render the gas active. For the purpose of destroying all insects in a room an exposure of about two hours to the gas are necessary, while for the destruction of bacteria an exposure of at least fifteen to sixteen hours is required.

In the application of disinfection with sulphur dioxide, as with any other gas, it must not be forgotten that gases very readily escape through the many apertures, cracks, and openings in the room and through the slits near doors and windows; and in order to confine the gas in the room it is absolutely necessary to hermetically close all such apertures, cracks, etc., before generating the gaseous disinfectant. The closing of the openings, etc., is done by the pasting over these strips of gummed paper, an important procedure which must not be overlooked, and which must be carried out in a conscientious manner.

When sulphur is used in candle form the expense is considerably increased without any additional efficiency. When a solution of sulphurous acid is employed, exposure of the liquid to the air suffices to disengage the sulphur dioxide necessary for disinfection.

The quant.i.ty of the solution needed is double that of the crude drug, i. e., ten pounds for every 1,000 cubic feet of room s.p.a.ce.

=Formaldehyde.=--At present the tendency is to employ formaldehyde gas instead of the sulphur so popular some time ago. The advantages of formaldehyde over sulphur are: (1) its nonpoisonous nature; (2) it is a very good germicide; (3) it has no injurious effect upon fabrics and objects; (4) it does not change colors; and (5) it can be used for the disinfection of rooms with the richest hangings, bric-a-brac, etc., without danger to these. Formaldehyde is evolved either from paraform or from the liquid formalin; formerly it was also obtained by the action of wood-alcohol vapor upon red-hot platinum.

Formaldehyde gas has not very great penetrating power; it is not an insecticide, but kills bacteria in a very short time, and spores in an hour or two.

Paraform (polymerized formaldehyde; trioxymethylene) is sold in pastilles or in powder form, and when heated reverts again to formaldehyde; it must not burn, for no gas is evolved when the heating reaches the stage of burning. The lamps used for disinfection with paraform are very simple in construction, but as the evolution of the gas is very uncertain, this method is used only for small places, and it demands two ounces of paraform for every 1,000 cubic feet of s.p.a.ce, with an exposure of twelve hours. Formaldehyde is also used in the form of the liquid formalin either by spraying and sprinkling the objects to be disinfected with the liquid, and then placing them in a tightly covered box, so that they are disinfected by the evolution of the gas, or by wetting sheets with a formalin solution and letting them hang in the room to be disinfected.

The method most frequently employed is to generate the formaldehyde in generators, retorts, and in the so-called autoclaves, and then to force it through apertures into the room.

Of the other gaseous disinfectants used, hydrocyanic acid and chlorine may be mentioned, although they are very rarely used because of their irritating and poisonous character.

=Hydrocyanic Acid= is frequently used as an insecticide in s.h.i.+ps, mills, and greenhouses, but its germicidal power is weak.

=Chlorine= is a good germicide, but is very irritating, poisonous, and dangerous to handle; it is evolved by the decomposition of chlorinated lime with sulphuric acid. Chlorine gas is very injurious to objects, materials, and colors, and its use is therefore very limited.

_Chemicals Used as Disinfectants_

Solution of chemicals, in order to be effective, must be used generously, in concentrated form, for a prolonged time, and, if possible, warm or hot. The strength of the solution must depend upon the work to be performed and the materials used. The method of applying the solution differs. It may consist in immersing and soaking the infected object in the solution; or the solution may be applied as a wash to surfaces, or used in the form of sprays, atomizers, etc. The most important solutions of chemicals and the ones most frequently employed are those of carbolic acid and b.i.+.c.hloride of mercury.

=Carbolic Acid.=--In the strength of 1:15,000 carbolic acid prevents decomposition; a strength of 1:1,000 is needed for the destruction of bacteria, and a three per cent to five per cent solution for the destruction of spores. Carbolic acid is used, as a rule, in two per cent to five per cent solutions, and is a very good disinfectant for was.h.i.+ng floors, walls, ceilings, woodwork, small objects, etc. The cresols, creolin, lysol, and other solutions of the cresols are more germicidal than carbolic acid, and are sometimes used for the same purposes.

=b.i.+.c.hloride 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 b.i.+.c.hloride 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.

=Pota.s.sium 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 pota.s.sium 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 munic.i.p.al 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 furnis.h.i.+ngs, tapestries, etc., sulphur cannot be used on account of its destructive character; when sulphur is employed it is, as a rule, in the poorer cla.s.s 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 princ.i.p.al 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 s.p.a.ces 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 sc.r.a.ped 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 b.i.+.c.hloride 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.

=Gla.s.sware 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 b.i.+.c.hloride 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 lat.i.tude 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.