Bacteriological survey of "surface" water supplies.

Date:
[between 1890 and 1899]
Catalogue details

Licence: Public Domain Mark

Credit: Bacteriological survey of "surface" water supplies. Source: Wellcome Collection.

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

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    BACTERIOLOGICAL SURVEY OF SURFACE WATER SUPPLIES. There are two contending interests which the chemist and the bacterio- logist have to face when they have to give an opinion on any water supply. Firstly, they have to protect the consumer against any possible danger - that might arise from the use of bad water. Secondly, they have to consider the ratepayer, that is to say, they must not cause to the community any unnecessary trouble or expense by condemning, without good reasons, any source of water supply. It is my object in this communication to show how a bacteriological investigation may be carried out so as to meet the difficulties of the case and to protect all interests concerned. I have often been struck with the absence of -any sure guide to the interpretation of the results of bacteriological analysis of water. This difficulty has apparently been felt by most of the bacteriologists who have paid any attention to this question. Most writers allude to it without giving any solution, apparently reserving to themselves the liberty to use their own judgment in the interpretation of their results. Others have, on the contrary, laid down definite rules. Unfortunately, among the latter few will be found to agree with each other. Thresh (1896) rightly says that the attempt to set up a standard of purity based on the number of micro-organisms in a given quantity is as illogical as the old chemical standards. Having for several years acted on this belief, I am in perfect agree- ment with him. I cannot, however, altogether follow the same authority when he states : At the present time it is doubtful whether a biological examination really tells us more than a chemical analysis, and verv often it cannot tell us as much. During the last five years I have investigated bacteriologically the water supplies of some important towns, and have had the advantage of bang able to compare my results with those of my colleague, Professor H. Dixon, who examined chemically samples of nearly all the waters u Inch were exammed bacteriologically by me. J am quite satisfied ta both the chem.cal and the bacteriological examinations we e use ul A