THE TRUTH ABOUT SEWER GAS.

Globe, Volume XXIV, Issue 2666, 23 October 1882, Page 3

THE TRUTH ABOUT SEWER GAS.

[From the “ Lancet,” 12th Auguat, 1883.] It is with great satisfaction that wo already begin to see the fruit of our endeavor to press the truth about sewer gas on public attention, cropping up both at home and abroad, Brighton is, ill-tcmperedly it is true, and we fear awkwardly and expensively, but nevertheless after a fashion, stirring itself. Let us hope that when the folly of an irascible and misguided moment has been recognised and abandoned, the authorities of Londou-super-mare may be reasonable, ana accept the counsel, instead of resenting the remonstrance wo havo addressed to them. We claim to have been their true though candid friend in this matter, and the time must come, sooner or later, when they will themselves perceive this fact and recognise that onr solo object has been the purification of a “health rssort,” in which, on public grounds alone, wo havo a lively interest. Meanwhile there aro abundant evidences that what we havo written on the subject of sewer gas and sower ventilation, apropos the special needs or Brighton, has produced results far more extensive and salutary than even we had contemplated. Despite the ridiculous attempts made by some of our lay contemporaries to appease public anxiety, by representing the gaseous emanations from sewers es innocuous, if not absolutely healthful, it is beginning to bo recognised that the groat practical disadvantages of the “ mam drainage” and “intercepting sewer” system, whenever and wherever adopted, namely, the accumulation and return of sewer gas must be overcome before the requirements of public health can be held to have been absolutely satisfied. The necessity of the crisis in sewerage reform is to devise and adopt some efficient mode of ventilation, by which the vapors and gaseous products of decomposition given off by the sewage in its passage through the common sewers may be destroyed, or, if that be impossible, carried harmlessly away. Closed pipe* must and will retain, and under

certain condition! return, their vaporous and gaseous content*, unleis theie ore removed Dy a special system of ventilation. Open gratings in the street! of a populous district ( are not simply nnisanoes, but trap! for the unwary. So far from the assertion that a srhiff ol seWer gas ii not poisonous being true, it is a painfully well known fact —indeed it is a matter of common observation —that a purely casual inhalation may produce a peou-iarly marked effect. In regard to this, as to other poisons, it often happens that the viol™ ot the evil influence is the person who hat been for the shortest time and to the least extent exposed to it. It is 10 even with an odour. The dwellers in foul air beooma so habituated to it that they do not perceive the I ten oh that nauseates a chance visitor. _ Ihat this rule of tolerance applies to poisons is eo notorious that we can only marvel that it is not generally admitted. It is, however, a matter of little moment what may be said or written in apology for or defence of the status qus as regards sower ventilation. It is an incontrovertible fact that_ sewer gas i« poisonous, and the only question should bo, By what method or mean* are we to ge. rid of it P We have no epooialgleaning to and certainly no aort of interest in—any particular “system.” It is obviously necessary to discharge the gaa as far as possible out of the respired atmosphere, and consequently it cannot be right to Yentilate the aewera directly into the street*. This ia a Simple, common seme oonoluaions No question of the dilution of the poison by admixture with the air can possibly oome into consideration where the open grating system is adopted, because the pedestrian, or, if the grating be near an open window, the house occupier, inhales the mingled gas and vapour as it rises from the grating. It may not be perpetually given off, but it makes it way out—probably in gusts—-as the varying distribution of heat in the system of sewers and the relative temperature of the external atmosphere may determine The only rational mode of procedure, as it seams to us, is to ventilate the sewers by pipes rising above the level of the adjacent bouses, so that it may mingle freely with the higher strata of the atmosphere, and become oxidised. No one who has had any practical experience in ventilation ought to be ignorant of the fact that the atmosphere is stratified by the zones of heat and consequent currents that traverse and intersect. Even in a room some twenty feet square and thirteen feet high there may bo tbr.e or four practically distinct strata of the contained atmosphere, and a vapour or gas introduced at one level will not quickly rise or fall to another. The law of the diffusion and admixture of gases is easily suspended by conditions of looal temperature and the play of jots of cold air. Just as mists and fogs may roll on the ground, become entangled by trees, be interrupted by. the reverse current over a river, or hang suspended over tracts of land which are not yet affected by their presence, so sewer gas may be disseminated through certain strata of the atmosphere, and neither be dilated by nor affect other strata for an appreciable period of time, quite long enough to bring other conditions into operation, and render it ultimate disposal—the unexpected. The only sensible plan of dealing with a noxious gas or vapour is to destroy it locally where it is generated, or failing that, to disperse it at a higher level. This is the ooane of procedure we have recommended in dealing with sewer gas, and to that recommendation we adhere. The objection that snob a discharge is difficult, because when the sewers happen to be of a different temperature from that of the higher strata of the atmosphere—which it generally the case—a down current may bo set up in the ventilating pipes, is not worth discussing, because in practice the difficulty can be easily got over by employing pipes of different heights, the lowest always reaching above the roofs of the houses, the highest opening at a much greater altitude. When several pipes so arranged are connected with the same system of sewers, it will scarcely ever happen that even for a moment the outpour is interrupted. The discharging orifices lie in different strata, and with the protection of cowls the currents of the atmosphere act in a way that Is found to be compensatory. This i’, however, a matter of detail. We only alinde to it in passing to note the recognition of a difficulty which has been pointed out, and at the same time to indicate that there is a remedy close at hand. Our immediate object is, we hope, in a fair way of being attained, and we are glad.to know that mnoh collateral good has been done by the discussion in which we have been involved. Everywhere, and among all classes of the resident population, attention has been aroused, and many extensive and costly measures have been taken to remedy evils which were previously overlooked. There are two points we would again, and more strongly than heretofore, press on the notice of the public:—lst. The system of ventilating by street gratings must bs finally abandoned. In some parts of the metropolis the condition of matters in this respect is most unsatisfactory, 2nd. It is useless to trust to the ordinary traps for disconnecting housedrains from the sewers. This last-mentioned matter is within the control of every householder. Properly constructed disconnecting chambers should be fitted to every house. The present season, when families are leaving town, is, so far as London is oonoerned, a timely one to have this limited and not very costly measure of safety carried into effect. We venture to hops our suggestion will not be unheeded.