REPORTS 457 REPORTS. Metropolitan Water Board. Eighth Annual Report of the Director of Water Examination. A. C. Houston. April, 1914. (Published by the Board, price 2s. 6d.)-The most notable event during the year was the recurrence of algal trouble in the Staines reservoirs, due on this occasion to the growth of Asterionella, which rendered the water almost unfilterable. The remedy used was to treat the water with copper sulphate and to dilute it largely with raw river water.I n addition to the usual oxygen absorption test for three hours at 80” F., corresponding tests for four hours were made over a considerable period ; the results of the latter were 5 per cent. higher. In the case of unsatisfactory waters there was found to be a striking parallelism between the results of a five minutes’ oxygen absorption test and the usual three hours’ test. Taking 0.1 part per 100,000 as the basis for objecting to the quality of a water on the three hours’ test, the correspond- ing figure for the five minutes’ test was found to be 0,038.This test serves as an index to the probable quality of the water, and, when unsatisfactory, enables a communication to be made to the district concerned on the same day as the collection of the sample.The bacterial count on bile-salt agar, which the author considers to be the most reliable count for indicating undesirable organisms, had been confined previously to the raw river water, but was extended during the year to the filtered waters. The number of bacteria found in these latter samples on this medium averaged less than 1 per C.C.The result of the test is most reliable in winter ; occasionally in summer higher results are obtained, but the colonies are not of a typical appearance, and there may be a growth of bacteria in the water which are not necessarily of intestinal origin. I n returning the average number of bacteria in the raw river water, it has been customary to include all the results in the average, but at times of high flood counts of 25,000 have been obtained, and it is considered that if these high results were excluded, a more accurate average figure would be obtained.Also, as there is no reason why the intakes should not be closed at these times of high flood, the exclusive average figure would more truly reflect the quality of the water abstracted.Full tables with details of the chemical and bacteriological results for the raw and filtered waters throughout the year are given. It is considered that the means now adopted for the purification of the supply are such as to render the water reasonably, if not absolutely, safe for drinking purposes. J. H. J , Metropolitan Water Board. Eleventh Report on Research Work.A. C. Houston. (Published by the Board, price 2s. 6d.)-Two subjects are treated in this Report, the first being the author’s excess lime method of purifi- cation. This has been put into operation on a practical scale, and to Aberdeeu belongs the credit of being the first in this country to show that the laboratory ex- periments could be applied to the supply of 165,000 people, and applied success- fully.The water-supply is derived from the very soft water of the River Dee, and no attempt was made to remove the excess of lime before consumption of the water.4 58 REPORTS The amount of lime added was 3 parts per 100,000, and the water after treatment contained 2.17 parts of free lime i n solution and 0.45 part of carbonate of lime in suspension.B. coli were usually present in as little as 1 C.C. of the water when untreated, and were practically always absent from 100 C.C. during treatment. As a result of this temporary treatment, the Corporation has decided to adopt a permanent scheme based on this principle. The process has been applied to a hard river water at Sunbury-on-Tharnee-, and a detailed account of this experiment is given.About 168,000 gallons were treated daily with quicklime, at the rate of 2,000 pounds per 1,000,000 gallone, and three days’ contact in two settling tanks was allowed. The caustic alkalinity of the water after settlement was 6.86 parts per 100,000, and to neutralise this, stored river water was added in a third tank in the proportion of 4 : 1, and about three hours’ contact allowed.The water wai3 then passed through an ordinar sand filter. The resulting water on chemical analysis compared favourably with the ordinary supply to the Metropolis, and also B. coli mere never present. The author has no hesitation in expressing the opinion that river water, no matter how impure, can be brought to a condition of absolute safety bacteriologically, and of great relative purity chemically, by means of the excess lime treatment.The second subject dealt with in the Rgport was suggested by the ‘‘ world-wide war now raging,” which increases the risk oE epidemic water-borne disease ; and the author has made a further study of water organisms liable to bs mistaken for the true cholera vibrio. Peptone water cultures were made with 10 to 50 C.C.of London water, and the growth subcultured on agar. Likely colonies were inoculated into peptone water, and after twenty-four hours’ growth these cultures were tested for the cholera-red reaction. Out of 1,583 colonies, 80 gave the reaction, and kherefore required further study. Gelatine shake cultures were made, and 13 gave no gas, aud so were provisionally accepbed. These were then tested for liquefaction, and 5 ghve positive results. These were then grown in peptone water for forty-eight hours, and all failed to give the cholera-red reaction a second time; they were, therefore, not the true cholera vibrio. At the end of the Report is given an index to the author’s first ten Research Reports published during the last twelve years. The index refers in great detail to all the points treated in the Reports, and will be of great use to ofher workers who wish to consult them. J. H. J. + + + + + No complaints were received. Y