Pure Water Supply.

Daily Telegraph (Napier), Issue 6825, 2 August 1893, Page 3

Pure Water Supply.

« ■ Important Discovery. London, Jugs 10. Dr FnmMand —or rather Profo-sor Frankland, D.0.L., L L.D , M/'V, F.K.rf. —is not only one of tho mnst famous living (scientists, but U also the greatest authority in the world oil auestious relating to water supply iv connection with its quality and purity. He is special water analyst to the Looal Government Board, and in that oapaoity examines and reports upon the •water supplied to every importaut town ia —Ihe kingdom. H'B oftioiil laboratory is no; ia town but at his private residence at Ludgate Hill, one of the loveliest parts of rural Surrey, and here, iv several rooms devoted to thie importaut purpose, tho work o>. testing and analysis is always ia progress, most of the merely mechanical work beiug done by assistants While visaing Pr Frankland recently I obtained much valuable information and therefore permission to use it for the public good. His mothod of analysis ia that by combustion of re&iduum flfter evaporation. Hβ evaporates the water iv separate receptacles, and then treats the residuum by combustion with oxide of copper for deterinination of the amounts of organic carbon and organic nitrogen present. Iα this way the presence of organic impurity in infinitesimal proportion can be detected with certainty. He finds this plan immensely superior to the tlumey and less accurate permanganate mrthod. I do not mention this as a novelty, but merely as the matured view of the greatest authority. The process, however, is a somewhat troublesome one Mid also of exttetne delicacy ia operation. But a most valuable and important discovery has lately bern made iv relation to . the filtcatioii of water eupplios. Of even moro importance to the public health and safety than the freedom of drinking water from organic pollution is its freedom from bioterial impurity. The microbes of zymotic diseases are found to multiply with extreme rapidity in water, and thue the most deadly diseaees are widely by contaminated atreams or rivers, ur. Frankland has undertaken for a year the bacteriological examination of the London water supplies. ' The result hae been of great value. \ X He finds that by filtratim through sand the passage of microbes can be almost : wholly arrested, bo that the filtered water id practically, if not absolutely, free from their undesuablo presence. Tfcuc, by thw very simple and inexpensive modo ot filtration fe moat d.fldly of all the impurities of ' "water can be eliminated with an approximation to certainty, and shou'd a stray microbe succeed in finding his way through the sand, the chances that be may ba a pathogenic microbo are exceedingly small Hence, co far aa fallible humaa means can K o itntnuuity from infection by water carriage may be definitely secured if sand filtration bo adopted. This is a vast stride to have made iv a valuable branch of hygienic science. But there is more yet to be said. -• Ie pie often fancy," B'iid lit Frankland, "th.it tho filtering sand be frequently washed or else it will become itself a aoui cc of impurity and danger. This is a c iiupleto mistake. Oddly enough it turns out that the gelatinous film which collects on the mrface of the sand is in itself a most useful protection. - Of course it soon swarm.-s with bacteria, but I find that the bacterid first iv the field insist on keeping it to themselves and allow uo later bacteria to pass them. Kvery later • arriving microbe that reaches the gelatinous film ie instantly seized upon and devoured by the earlier arrivals, who appear to resent hia intrusion. Consequently, as long aa the impure film be not so douue as to obstruct the passage of the water, it actually affords valuable additional protection againat bacterial pollution." "This," continued Professor Trankland, " is an Immense boon, for I do not hositata to say that, should tho cholera visit us this Hummer, its diffusion by moans ot tho water supply— which wan so deadly in fornv.T visits-is now -virtually impossible if the ■water companies ket-p their filtration up to tho mark, which they appear fully determiaed to do, and which, in any case, they must be made to do. In tho cholara visitation of 1849 water mostly unfiitered was supplied, and 14,137 persona died of cholera. Iv that of l>6l unfiltored water was tupplied, and 1O,7"8 people ciiod. In 1806 one company supplieU for a few days only un-filter-.d water, and tho opidtmio was almost confined to the area of that company's supply, but it killed 559G people, or 18 per 1000 of the entiro population of London ! Ho important has filtration become in the light of recent bacteriological research, that in the use for domestic purposes of river water receiving either sewage or sewage effluents, I would stiongly recommend double filtration as affording a second line of defence against the invasion of pathogenic microbes; but, of course, gravel water would not need double filtration." In view of tho occaeiocal prevalence oi typhoid fever and diphtheria ia New Zealand, Dr. Frankland thought baud filtration ■was urgently dteirable and quite feabiblein the case of the city wiiUi supplies, whilo the cOft would not be t-xcescive. These suggestions seem to mo so valuable, corniug from the higheht living authority, that I send them for the consideration of the New Zealand inuniuipal bodies interested ia quostions of water supp'y- Otugo Daily Times coirespondent.