June 1st, 1SS7.] 



SCIENTIFIC NEWS. 



81 



branch-sewer carried right under the flooring-boards of 

 dwelling-rooms. Such sewers consist of earthen pipes, 

 not cemented together, but merely puddled with clay, 

 which gradually crumbles away and allows of the escape 

 not merely of gases, but of liquids also, which by degrees 

 form a putrid pool underneath the house. 



It is important to put on record that some little time ago 

 the medical officers of health of all the metropolitan dis- 

 tricts unanimously recommended that no such branch- 

 sewer should be in future carried underneath the floor of 

 any house, unless duly cemented and embedded in concrete. 



Ground-air is a possible source of disease, which was 

 completely overlooked until its existence was pointed out 

 by Professor von Pettenkofer. Every one must see that 

 the pores of the ground, unless waterlogged — which is not 

 a desirable state of things — must be filled with air, and air, 

 generally speaking, of a bad quality. Organic matter of 

 different kinds is washed down into the earth by rain, and 

 there passes gradually into decomposition. The soakage 

 from cesspools, graveyards, etc., yields a plentiful supply 

 of putrescent matter for the pollution of the ground-air. 

 The case is perhaps worst in houses built upon what is 

 called " made-ground," where hollows and excavations 

 have been filled up with any and every kind of refuse 

 which was at hand. 



But it may be asked, why should this ground-air dis- 

 charge itself into our houses, rather than in the roads and the 

 courtyards ? The reason is twofold — on the one hand the 

 air of a house is generally warmer than that outside, and 

 being thus expanded rises upwards, just as in a chimney. 

 In so doing it draws the ground-air upwards. Another 

 point is that the surface of the ground in the streets and 

 courts is made, comparatively speaking, air-tight by flag- 

 ging, paving, or asphalting. Hence the surface under a 

 house is the region of least resistance, and there, accord- 

 inglj', the gases from below find vent. 



It would be a great improvement if the ground upon 

 which a house stands were well coated with concrete or as- 

 phalte so as to cut off this ascending current. 



Dr. W. B. Richardson, when describing his imaginary 

 model city, Ilygeia, proposes that the houses should be built 

 upon a series of arches, so that a current of free air might 

 always be able to play between their foundations and the 

 ground. This, from a sanitary point of view, would be a 

 most excellent arrangement, but, like some other of the 

 learned doctor's suggestions, it is impracticable on economic 

 grounds. Houses so constructed would be too costly for 

 all except the rich. Hence we must limit our aspirations 

 to the asphalting of the ground underneath our dwellings 

 and the banishment of sewers placed under their floors. 



But even when sewer gases and gi ound-air are completely 

 excluded from a house its atmosphere is constantly be- 

 coming vitiated, and requires, therefore, continual renova- 

 tion. One of the chief causes of this deterioration is, as is 

 pretty generally known, the decrease of oxygen and the in- 

 crease of carbonic acid, due to the respiration of the in- 

 mates. In crowded rooms not duly provided with facilities 

 for ventilation the oxygen may fall from its normal standard 

 of 20.8 parts per cent, by volume down to 20, or even 

 lower, whilst the carbonic acid gas may lise from 0.04 per 

 cent, to more than double that quantity. In such propor- 

 tions it occasions languor, headaches, and, if habitually 

 breathed, it brings on a state of general debility, which pre- 

 disposes the sufferer to the attacks of any disease. 



Yet, paradoxical as it may sound, this excess of carbonic 

 acid is not the most objectionable ingredient in the air of an 

 ill-ventilated room. In fact, the most able sanitarians view 

 it chiefly as an index of animal pollution. Wherever it is 

 found in abnormal quantities, and where there is no source 



for its production save the respiration of human beings, 

 there will also be found an excessive quantity of animal 

 matter, either as a vapour or in minute solid particles. 

 This animal matter quickly putrefies, and to it is due that 

 peculiar smell found in ill-aired and overcrowded rooms, 

 and known familiarly as " stufliness." This smell adheres 

 to the clothing, to the hair, and generally to the persons of 

 the inmates, and is at once recognised by medical men as 

 proof that a patient, e.g., in the hospital, has been living in 

 bad air. 



We have been supposing that the inmates of a crowded 

 dwelling are all in a normal state of health ; but if any of 

 them are sick, even of some disease not recognised as in- 

 fectious, the case is much worse, and the need for ventilation 

 is far greater. The animal matter thrown off from the 

 skin and the lungs of a diseased person is greater in quan- 

 tity and dift'erent in quality from that which emanates from 

 a healthy man. 



In most cases, indeed wherever practicable, no pers m 

 suffering from any disease should remain in a room in 

 which other persons have to sleep or eat. 



We have, in passing, mentioned the products of com- 

 bustion as taking no small share in' polluting the air of our 

 houses. Lamps, candles, gas-burners, stoves, consume 

 oxygen and throw off carbonic acid just as do living animals. 

 Indeed, it is no easy matter to draw a sharp distinction 

 between life and combustion. 



However, carbonic acid is not the only undesirable pro- 

 duct of combustion. Wherever the supply of oxygen is not 

 fully proportionate to the carbon, carbonic oxide, or, as it is 

 now called, carbon monoxide, is generated. This gas is far 

 more harmful than carbonic acid. It is fatal even if mixed 

 with common air, or with oxygen in very small proportions. 

 In a method of suicide much in vogue in France, where 

 a person weary of life shuts himself up in a small room 

 with a chafing-dish of burning charcoal, carbon monoxide 

 is in fact the chief deadly agent. 



Another objectionable product of the combustion of coal 

 and coal-gas is sulphurous acid. All coals and all coal-like 

 bodies, except, perhaps, far-famed Tortane Hill mineral, 

 now no longer to be procured, contains sulphur. This 

 sulphur, on burning, is converted into sulphurous acid, which 

 in the case of gas flames escapes into the room. Every one 

 knows that sulphurous acid, if in sufficient quantity, occa- 

 sions death by suffocation, and, e.g., in the underground 

 railways it is very annoying to persons whose lungs are 

 sensitive. But in houses it seldom reaches a proportion at 

 all dangerous to health, though it is very destructive to 

 books, pictures, textile goods, and articles of polished 

 metal. 



Both carbonic oxide and sulphurous acid find their way 

 into a room most readily if coal or coke is burnt in a cast- 

 iron stove not placed under a chimnej'. Iron at high 

 temperatures allows these gases to pass through its pores. 

 Closed stoves built of Dutch tiles, stoneware, etc., are, 

 however, perfectly safe. 



Perhaps the most effectual means of securing bad air in 

 a room is to heat it with a chimneyless gas-stove. We have 

 seen devices of this kind where, in the hope of arresting 

 the carbonic acid, a dish of cream of lime was placed at 

 some height above the burners. But lime is quite unable 

 to absorb carbonic oxide, so that the more dangerous gas 

 passed freely into the room. 



Perhaps we may best wind up this sketch of the ventila- 

 tion question by suggesting a very simple method forjudg- 

 ing of the quality of the air in a room. If you step out for 

 a moment into the open air and on returning find a 

 " stuffy " smell you may know that the ventilation is in- 

 sufficient. 



