SCIENTIFIC NEV/S. 



[June 1st, 18S7. 



DOMESTIC SANITATION. 



No. 2. — Ventilation. 



PURE air is, if anything, even more essential to our 

 well-being than pure water. We may dispense with 

 water, or, indeed, with drink of any kind for hours in 

 succession, but very few of us could survive the total 

 deprivation of air for even five minutes. It is fortunate, 

 therefore, that no enterprising company can monopolise the 

 air-supply of any district, and dole it out to the consumer 

 in such quantities and of such a quality as they may think 

 proper. 



But, on the other hand, we cannot improve our air-supply 

 as we do our allowance of water. We may dip up from a 

 stream or a well a pailful of water, and by Clarkising, by 

 judicious filtration, or by the addition of a pinch of alum — 

 as the Chinese have done from time immemorial with their 

 foul river-waters — we may render it capable of being used 

 with safety. But with air we have no such resources. We 

 cannot have in our dwellings an atmosphere purer than 

 that outside, and unless we are careful it may become very 

 much worse. 



To prevent it from being thus deteriorated is the one aim 

 of domestic ventilation. 



To this end we have to allow the plentiful entrance of 

 fresh supplies of air from without ; to prevent the entrance, 

 as far as possible, of" ground air " and of sewage gases ; and 

 to arrange for the quick escape of such air as may have 

 become vitiated by the respiration of the inmates, by the 

 emanations given off from their skins, or by the products 

 of the combustion of gas, lamps, etc., and the smoke which 

 escapes from our chimneys. 



The quantity of air which should be supplied to a room 

 has been very variously estimated. Dr. Neill Arnot and 

 Sir H. Roscoe take twenty cubic feet per minute for each 

 occupant. But it is plain that the loftier a room, and the 

 larger with relation to the number of persons present, the 

 more slowly will a change of air be required. In good 

 dwelling-houses five cubic feet per minute for each inmate 

 will generally prove sufficient. But in schools, barracks, 

 theatres, churches, and, above all, in hospitals, twenty feet 

 will certainly not be excessive. 



A large allowance must be further made for artificial 

 lights, especially for gas. One gas-burner whilst in action 

 will spoil as much air as do three men. The electric glow 

 light has here the advantage over all other sources of artificial 

 light, that it does not vitiate the atmosphere at all. 



The next question is, where should the supply of air be 

 admitted ? The answer is, in the first place, not near the 

 surface of the ground, as there it is most likely to be pol- 

 luted with dust, the emanations of the soil, etc. Nor 

 should it enter dwelling-rooms through passages, cellars, 

 outhouses, and, above all, through water-closets, but as far 

 as possible directly from the open outside. Windows are 

 generally better inlets than doors. 



As regards the manner of introducing the air-supply, 

 there are two main systems. In the one, fresh air, drawn 

 from suitable points, and warmed to some convenient 

 temperature, is forced into a house, and drives the impure 

 air out at any and every opening. This system is the best 

 where practicable. Unfortunately, it is rarely available in 

 private houses, as a source of motive power is needed to 

 work the forcing pump. 



In the other system the vitiated air is drawn out through 

 the chimneys, through special shafts, at the windows and 

 doors, whilst fresh air rushes in at every opening and 

 crevice to take its place. 



This system requires no special machinery ; a Neill 

 Arnott's valve-plate opening into the chimney just below the 



ceiling will let the foul air escape whenever there is a fire 

 in the stove. Or should a downward draught occasionally 

 get the upper hand in the chimnej', the valve closes auto- 

 matically, and prevents the smoke and combustion gases from 

 entering the room. 



In fine weather almost all the necessary ventilation may 

 be effected by simply opening the windows, preferably both 

 at top and bottom. But in frost, fog, driving rain, and 

 northerly or easterly winds, this expedient is not admis- 

 sible. Hence a pane of glass may be provided near the top 

 of a window, drilled with a number of fine holes. Or in- 

 stead of the pane, there may be let into the window a frame 

 fitted with louvre-plates of glass. 



One channel through which the outside and the in- 

 side air are constantly interchanging is not generally 

 known. It takes place through the walls themselves, through 

 brick, free-stone, plaster, and through ordinary paper-hang- 

 ings. That such an interchange of air does take place may 

 be proved by a very simple experiment. We take an ordi- 

 nary brick and coat it completely over with a good varnish, 

 leaving uncovered merely two circular spots about the size 

 of a shilling, and exactly opposite each other. If when the 

 varnish is dry we apply the lips to one of these bare spots 

 and blow strongly, the blast may be distinctly felt coming 

 out at the other. By slightly modifying the experiment, it 

 is even possible to blow out a candle through the brick. 



If we consider what a relatively large surface the walls of 

 a house present, and that this interchange of air is taking 

 place day and night through every square inch of this sur- 

 face, we shall see that we have here a very important agent 

 in the supply of fresh air. All this holds good, however, 

 only so long as the ordinary building materials are used. If 

 the walls of a house are coated inside or out with oil-paint, 

 or lined with varnished paper-hangings, this channel of ven- 

 tilation is cut off, and the entire task is thrown upon the 

 windows, doors, and chimneys. 



Some kinds of stone are also air-tight. White marble 

 palaces are doubtless charming to read of in poems and 

 novels, but they do not allow of the free interchange of air, 

 and are consequently damp and stuffy, except in climates 

 which admit of large windows standing open at all seasons 

 of the year. 



On this same peculiarity a very plausible suggestion for 

 utilising the slag from blast-furnaces has been shipwrecked. 

 It was proposed to cast the slags in the form of large blocks, 

 and to use them in building houses. They have, in fact, been 

 used with success in erecting sheds, walls, etc., in manu- 

 facturing establishments. But when they were tried for the 

 outer walls of houses, it was found that the plaster did not 

 dry within any reasonable time. 



We must now take a glance at the evil airs and gases 

 which should by all means be excluded from our houses. 

 Foremost amongst these ranks sewer gas. This term serves 

 to include all gases and vapours given off from putrefying 

 excrements, and, generally speaking, from organic matters. 

 The nature of these gases, and the manner in which they 

 may serve as vehicles of disease, we shall endeavour to ex- 

 plain on some future occasion. For the present we must 

 consider the manner in which they find entrance into our 

 houses. Foremost come water-closets insufficiently trapped ; 

 then follow wash-basins in bedrooms and dressing-rooms, 

 connected with the sewer, and capable of being emptied by 

 merely drawing a plug. When this is done, down rushes 

 the water, and up comes in its stead a volume ef sewer-gas. 



Untrapped or insufficiently trapped sinks act in precisely 

 the same manner. The leaden soil pipes from water- 

 closets often allow of the escape of sewer-gas, since the 

 metal in course of time becomes corroded and presents a 

 number of chinks and perforations. Worst of all is the 



