The defence services

PUBLIC H E A L T H continued action of chlorine during transit would make the difference between a good and a bad water. It would, in my opinion, be a most dangerous practice to allow any such assumption to play a part in the technique of bacteriological tests performed with a view to the control of purification processes. The influence of chlorine in the sample bottle would depend upon several factors such as the time between the drawing of the sample and the inoculation of the media, the concentration of chlorine, the chemical constitution of the water, and the temperature, but it can be definitely stated that no reliable indication of the bacteriological state of the water going into supply, either at the time of drawing the sample or indeed at any other specified time, can be obtained from an analysis of a sample which contains active chlorine and which has been transported to the laboratory without the prior neutralisation of that chlorine. It has frequently been suggested and, indeed, the suggestion is repeated in Dr. Seyler's letter, that the time spent in the sample bottle may be accepted as the equivalent of the contact time usual in the mains. Even were these periods of similar duration, this suggestion could not be accepted, because conditions which materially influence the bactericidal velocity of chlorine may be, and usually are, quite different in the bottle and in the main. It has been my experience that, in some mains, chlorine and chloramine are rapidly dissipated. It can, moreover, be definitely accepted that if the residuum which is passed into supply is sufficient to be of value in the mains, a contact period in the sample bottle of only a fraction of the time usually taken in transporting a sample to the laboratory may completely transform the picture obtained. As suggested by Dr. Suckling, there can be no doubt that the wide discrepancies reported by Drs. Hughes and Wordley were not due to sampling errors but to defects in technique, or the employment of unsuitable methods of analysis. The Ministry of Health has, after serious consideration and consultation with authoritative opinion, drawn up Report No. 71 (Revised Edition, 1980) in which they have correlated tests and suggested standards for a routine in water examination. If the methods subscribed to in this memorandum were universally employed and the technique followed in detail by all laboratories examining water supplies, there is no doubt that a very much greater degree of accuracy and consequently of conformity in results would immediately be achieved. Unfortunately, many analysts consider that the methods they employ have served them well for many years and can see no reason for change, but it is held that the action of the Ministry has provided a much-needed opportunity for the standardisation of methods which should not be neglected. If analysts are unwilling to accept this opportunity, it is suggested that Water Undertakings and Local AUthorities could bring about the imposition of the desired standards by including a clause iu all agreements for bacteriological analysis of water supplies to the effect that they shall be performed in accordance with the methods and by the technique prescribed in Report No. 71. In laboratories which have maintained

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JULY records over long periods it is not always possible to change the methods suddenly or too rapidly. This is the case in the laboratories of the Metropolitan Water Board and although much has already been done in an endeavour to conform to the methods advocated in Report No. 71, certain changes still remain to be made. The outstanding reforms will be introduced as opportunity offers. If the policy of standardisation is to achieve a full measure of success, the Ministry must ensure that the best methods are available to all by the publication of revised editions of Report No. 71 as often as is necessary. Yours faithfully, E. F. W. MACKENZIE,

Director of Water Examinafion. Metropolitan Water Board Laboratories, 177, Rosebery Avenue, E.C.4. June 7th, 1940.

T H E DEFENCE SERVICES ELLISTON, G. L. C. (Executive Secretary, Soc. M.O.H.), Temp.. Sub-Lieut., R.N.V.R. KELM~% R. P. S. (Med. Supt., Selly Oak Hospital, Birmingham), appointed Lieut.-CoL, R.A.M.C. WILLOUGHBY, HUGH M. (Dep. M.O.H., Port of London Authority), Surg.-Cdr., R.N.V.R., was promoted from Surg.-Lieut.-Cdr. in November last.

London School of Hygiene and Tropical Medicine (UNIVERSITY OF L O N D O N ) Incorporating the Ross Institute It Is hoped to hold courses of instruction during the session 1940-41 for The Diploma in Public (University of London) and for

The Diploma and Hygiene

in T r o p i c a l (Eng.)

Health

Medicine

The course for the D.P.H. will last an academic year of nine months and the inclusive fee will be £56 14s. 0d. The course for the D.T.M. & H. will last five months and the inclusive fee will be £40 0s. 0d. Both courses will begin on Monday, 30th September, 1940. Those wishing to enrol should apply to the Secretary as soon as possible. Studentshlpa. In the D.P.H. course: The Chadwick Bursary, value £56 14s. ; and in the D.T.M.& H. course: the Andrew Balfour Studentship, value £15. For additional information apply to the SECRETARY, L O N D O N SCHOOL OF HYGIENE A N D TROPICAL MEDICINE, KEPPEL STREET (Gower Street) LONDON, W.C.I. (MUSeum 3041). _

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