I30 



NA rURE 



\Dec. \o, 1885 



and especially by a decrease in those diseases which are 

 now generally recognised as preventible. Thus, since 

 attention has been paid to the amount of cubic space and 

 the supply of fresh air per head in barracks, the death-rate 

 from phthisis or destructive diseases of the lungs in the 

 army has fallen from 10 to 2 per 1000; and typhus, 

 formerly very prevalent in the gaols of the country and in 

 the crowded courts of our large cities, is now almost 

 unknown in these situations. That there is still a vast 

 amount of disease and death which could be prevented by 

 a more general recognition of the absolute importance of 

 a pure supply of fresh air under all conditions, is a fact 

 whose truth we recognise when we observe the numbers 

 of scrofulous and ricketty children and consumptive 

 adults in our large centres of population. Many houses 

 in the poorer parts of towns are absolutely debarred from 

 obtaining fresh air and light by their surroundings. Built 

 almost back to back, or fronting into narrow courts or 

 passages closed at one or both ends, the sunlight never 

 penetrates for months in the year, and a free current of 

 air is an impossibility. Fortunately the Legislature has 

 recognised this evil, and the Acts known as Sir Richard 

 Cross's and Torrens's are intended to remedy such a state 

 of things, and, where enforced, have succeeded in removing 

 buildings which no structural alterations could improve. 

 The erection of huge blocks of Industrial Dwellings, 

 whilst affording vastly superior accommodation to the 

 working classes, has not always secured efficient ventila- 

 tion in these respects for certain of the tenements. We 

 have seen instances of lofty blocks being built in such a 

 way as to enclose a narrow and well-like court, in which 

 the atmosphere is always stagnant, and from which the 

 inner rooms derive all their light and air. Cottage build- 

 ings, with sufficient space in front and rear, are far 

 preferable to lofty blocks placed in rows ; but as they do 

 not house the same number of people for the space oc- 

 cupied in crowded districts, where land is of such enormous 

 value, the rents must necessarily be higher, the other 

 accommodation being the same. The air of enclosed 

 courts is often damp, and being stagnant allows suspended 

 particles to fall and foul gases to accumulate in it, thus 

 forming a suitable " nidus " for the growth and cultivation 

 of such disease germs as are capable of existing in the 

 air. It is true that the death-rates appearing in the 

 reports of many of the Industrial Dwellings Companies' 

 are exceptionally low, but we must remember that a ver\- 

 large proportion of the working clases die in hospitals and 

 not in their own houses, and such sources of error require 

 to be very carefully eliminated. Of late years Artizans' 

 Dwellings have been built on better principles, the ex- 

 perience derived from the sanitary failures of certain of the 

 earlier erections having been taken to heart. 



In the model bye-laws of the Local Government Board 

 it is provided that no new street is to be less than 36 feet 

 in width, that the frontage of any new building not stand- 

 ing in a street shall be at least 24 feet in width, and that 

 there shall be an open space at the rear of any new build- 

 ing and belonging to it of an aggregate extent of 150 square 

 feet, this space not to be in any case less than 10 feet 

 wide, and if the height of the building exceed 35 feet, to 

 be not less than 25 feet wide. If these rules could be 

 always enforced in the cases of new buildings an improve- 

 ment would be gradually effected in and around towns in 

 the poorer districts which is greatly needed. 



From what has been said it will be seen that one of the 

 principal points in any system of ventilation is that the 

 air to be admitted into a building should be pure, and 

 this can be ensured if there is no impediment to the free 

 circulation of currents of air on the outside. We come 

 now to the second part of the subject, viz. the vitiation of 

 air that is constantly going on in inhabited places from 

 the respiration of men and animals, and from the com- 

 bustion of gas, lamps, and candles, and the methods by 

 which this vitiated air may be replaced by pure external 



air. The composition of the atmosphere is as follows in 

 1000 parts : nitrogen, ygo'o ; oxygen, 209'6 ; carbonic acid 

 gas, '4, and traces of ozone, ammonia with nitrous and 

 sulphurous acids in the air of towns, and a variable 

 amount of aqueous vapour. The air taken into the lungs 

 of a human being has this composition, but that expired 

 differs from it in the following particulars, the nitrogen 

 remaining the same : the oxygen which is the vital 

 principle of air is diminished 4 per cent., the carbonic 

 acid is increased 4 per cent., the expired air is saturated 

 with aqueous vapour and is heated nearly to the tempera- 

 ture of the body, 98" Fahr., and contains a small proportion 

 of foul, decomposing organic matter, which exists partly in 

 the form of vapour and partly as solid suspended matter 

 (epithelial dust and scales). This organic matter, though 

 small in amount, is the most injurious C|uality of expired 

 air, giving to the atmosphere of an ill-ventilated room its 

 close and disagreeable smell. Those who are familiar 

 with the interiors of courts of law, with the pits and 

 galleries of theatres, or with crowded buildings generally, 

 are also familiar with the headaches, the lassitude, and 

 the " malaise " produced by breathing for some hours a 

 vitiated atmosphere. In analyses of such air nearly ten 

 times more carbonic acid has been found than is normally 

 present in the outer air, and when this excess is known to 

 mean a deficiency in oxygen and a corresponding e.xcess 

 in organic vaporous exhalations and suspended matter 

 from the breath and bodies of the persons present, the 

 foul nature of the atmosphere can be realised. The slow 

 deterioration in health, which results from the constant 

 breathing of foul air, is one of its most important results, 

 and causes a predisposition to, and lessened power of, 

 resistance to attacks of disease. 



An adult man of average size takes in and breathes out, 

 when at rest, about 30 cubic inches of air at each respira- 

 tion, this act being performed about seventeen times in a 

 minute, so that in one hour about 1 7 cubic feet of fresh air 

 will have been vitiated to the extent of containing 4 per 

 cent, of carbonic acid — that is to say, about 7 cubic foot. 

 Such a man gives out when at rest, therefore, nearly 7 

 cubic foot carbonic acid gas per hour. Now it has been 

 found by Dr. De Chaumont, by chemical examination of 

 a large number of samples of the air of inhabited rooms, 

 that the amount of carbonic acid in the outer air being '4 

 per 1000, no close smell is perceived in the air of a room 

 until the carbonic acid reaches '6 per 1000, or exceeds by 

 •2 per 1000 that in the outer air, the close smell being 

 always due to the foul organic matter in the impure air, 

 which increases pari passu with, and is therefore estimated 

 by the amount of carbonic acid present. It has been 

 assumed by De Chaumont, and experience has fully con- 

 firmed this assumption, that we can breathe with immunity 

 air vitiated to this .slight extent, but that we should not 

 allow any greater vitiation. We may take it, therefore, 

 that the object of ventilation is to supply sufficient pure 

 air to a room to prevent the carbonic acid rising above '6 

 per 1000, this cjuantity being known as the limit of re- 

 spiratory impurity. It may be asked why should not the 

 air of our rooms be as pure as the air outside ? No doubt 

 this would be desirable, were it not that it involves a con- 

 tinual renewal of the inner air by the outer, which means 

 in cold weather an unceasing draught at an unbearable 

 temperature. We have seen that an ordinary adult man 

 expires 7 cubic foot of carbonic acid in one hour when at 

 rest, now if such an individual were enclosed in an airtight 

 chamber, 10 feet high, 10 feet wide, and 10 feet long — that 

 is to say, in a chamber containing I030 cubic feet space — in 

 one hour the carbonic acid in this chamber would have 

 had added to it 7 cubic foot of carbonic acid : the air 

 originally contained '4 parts of carbonic acid in 1000 parts, 

 so that after one hour it would contain 4 + 7 = V\ parts 

 of carbonic acid per 1000, or ri-'6 — '5 parts per 1000 

 above the permissible limit for health. But if the subject 

 of our experiment were enclosed in a room containing 3500 



