An inquiry into the relative efficiency of water filters in the prevention of infective disease / by G. Sims Woodhead and G.E. Cartwright Wood.

  • Woodhead, German Sims, Sir, 1855-1921.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: An inquiry into the relative efficiency of water filters in the prevention of infective disease / by G. Sims Woodhead and G.E. Cartwright Wood. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    In this experiment it will be seen that the filtrate remained sterile up to the eighth day, which is a period of time at least double that during which the Pasteur-Chamberland gives a sterile filtrate under similar conditions. The experiments with this material as a tap filter were carried out during the colder season of the year, when undoubtedly Tablb cm.—Thames Water taken at Waterloo Bridge. iSt ray. . and Day. 3rd Day. 4th Day. 5th Day. 6th Day. 7th Day. 8th Day. glh Day. 10th Day. nth Day. 12th Day. + + + + the temperature conditions are much less favourable for the growth of water organisms through the filter, and where, accordingly, the filtrate would tend to remain sterile during a longer period. The temperature of the water during the first experiment varied from 16° C. down to 12° C, but we may mention that during this period Chamberland and Berkefeld filters under precisely similar conditions failed to discharge continuously sterilised water. The results are set out in Table CIV. These results with water are certainly very striking, and indicate that at any rate when exposed to a moderately low temperature this filter can apparently supply a sterile filtrate for at least a month. We have already pointed out that the .growth of water organisms through the walls of the candle into the filtrate does not in any way indicate the incapacity ■of a filter to prevent the transmission of waterborne disease, so that the power possessed by this filter of ofiering greater resistance to the passage of water organisms does not neces- sarily indicate more perfect protection against cholera and typhoid, although it undoubtedly does show that in this material we have an extremely effective filtering medium. The very fine nature of the porcelain would no doubt mani- fest its influence most markedly in the case of the filtration of fluids containing toxic bacteria, but, as has already been discussed elsewhere, it is very doubtful whether such refine- ments in the action of a filter such as those which exist between the d'Amiante, Chamberland and Berkefeld filters would exert any perceptible influence in actual use. We have carried out experiments with tap water and emulsions of cholera (Table CV)and typhoid bacilli (Table CVI) over prolonged periods, using the two forms as table filters. In no instance have we been able to demonstrate the presence of either of these organisms in the filtrate. These experiments prove that this filter provides as perfect a protection against the transmission of waterborne disease as is afforded by any of the methods of filtration at present known to scientific workers.