Koch's Gelatine Process for the Examination of Drinking Water

Abstract

I AM much indebted to Mr. Scudder for furnishing an opportunity for calling attention to a misapprehension which appears to exist in some quarters as to the time and manner in which Dr. Koch's method of water examination by the process of gelatine-plate-culture was introduced into this country, as but for his letter I should not have thought it worth while to discuss a matter which must be sufficiently well known to all who are really conversant with the development of bacteriological inquiry in Great Britain during the past fifteen years. In the first place, I would point out that in making the statements referred to by Mr. Scudder, I did so with the full cognisance of the late Dr. Angus Smith's work as published by him in his second Report to the Local Government Board, and in an article of his which appeared in the Sanitary Record in 1883. In this work I was so much interested that I at once, in the same year, set about applying the method described by Dr. Angus Smith to a number of the samples of London and other waters which were being subjected to analysis in my private house at the time. These experiments yielded, however, such indefinite and unintelligible results that I entirely abandoned Dr. Smith's process, and it was not until the summer of the following year (1884) that I became really acquainted with Koch's method of plate-cultivating bacteria through the now classical demonstrations given by Mr. Watson Cheyne at the Health Exhibition. It was this method of gelatine-plate-culture which I then immediately applied to the investigation of a number of problems connected with the bacterial purification of water by filtration, precipitation, &c, both on the laboratory and on the industrial scale, and the results of which I placed in the hands of the Royal Society in May 1885, in a paper entitled “The Removal of Micro-organisms from Water.” It is this paper which I believe to be the first published account in this country of the application of what is now universally understood as “Koch's gelatine-plate-process” to the examination of water, and the first to contain numerical determinations of the bacteria present in a given volume of the various waters supplied to London. In the autumn of the same year (1885) I undertook, at the request of the late Sir Francis Bolton, then Water Examiner for the Metropolis, to make for the Local Government Board regular monthly examinations by this process of the various waters, both before and after filtration, supplied by the several London Water Companies, and the results of these were regularly published in the monthly reports issued by the Local Government Board.