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and the means of their elimination from water were taking place in America and in Britain. In London much work had been done by Frankland, Crookes and Tidy on all aspects of water supply problems to towns and cities; such as the effect of lead piping, the softening of hard water, the causes for and the elimination of corrosion in boilers, the prevalence of household wells and the need for properly organised communal supplies, harmful micro-organisms in potable water and their removal not only by filtering but by chemical additives and, of course, taste. James Dewar had for many years been interested in these matters and on the death of Dr Tidy he became associated with Sir William Crookes in the daily analysis of the water supplied by The Associated Water Companies of London whose premises were at 14 Colville Road. As London’s population grew the need for a reorganisation of the structure of the eight separate Water Boards became apparent. Rationalisation was required. The Water Act of December 1902 made The Metropolitan Water Board responsible for providing the chemical and bacteriological examination of the water supplied to its customers. At the ‘appointed day’ the water supplied by all the companies was subjected to scrutiny by Sir William Crookes and Professor Dewar. This increased greatly the volume of their work. In 1900 the number of examinations was six thousand seven hundred and thirty one. By 1904 it had risen to nine thousand one hundred and forty six. Requested to report on how to place the examination o a more uniform basis Sire William Crookes and Professor Dewar came to the conclusion, presented to The Metropolitan Water Board in May 1905, that a central laboratory adequately equipped where samples of raw and of filtered water would be thoroughly examined should be erected and that it should be staffed by a full-time officer and assistants. Their recommendation was accepted. New purpose built laboratories were constructed and in July Dr A. C. Houston was appointed as the officer in charge and from 31st October 1905 Sir William Crookes and Professor Dewar were relieved of their responsibilities. By their own report they had made themselves redundant from what had been a very remunerative part-time appointment (note 27).
To James Dewar the liquefaction of gases was not an end in itself. He always had in view the utilisation of liquid gases in furthering research in different fields of enquiry and so he applied the liquid gases to a wide range of pioneer explorations of the properties of matter at very low temperatures – chemical and photographic action – phosphorescence – and the cohesion and strength of materials. The liquid gases were new tools which science could use and no one was more enthusiastic in using them than Dewar himself. To do so efficiently he had to call in scientists who were authorities in other disciplines and so there began a long and fruitful association with many co-workers in widely different areas of research. Only very lightly can one, in a brief study such as this, touch on this aspect of James Dewar’s many activities. One fellow scientist with whom he had a long and profitable partnership was Sir J. Ambrose Fleming with whom he studied electric and magnetic effects such as conduction, thermo-electricity, dielectric constants and magnetic permeability. Like Dewar, Fleming, who is remembered for his invention of the Fleming valve, concerned himself not only with theory, in his case the theory of electricity, but with the practical application of his discoveries. Their collaboration began in the late 1890s and one of the staff recalls how familiar they became with Dewar’s loud and hearty greeting to his colleague – “Marnin Fleming” – in his strong Scottish accent. One of Fleming’s assistants tells how, with Dewar, Fleming studied the electric resistance of metals and alloys at very low temperatures. The actual resistance coils were made at Fleming’s laboratory in University College and brought to The Royal Institution where the resistance of these coils at –78 degrees Celsius and –182 degrees Celsius was measured when liquid air or liquid oxygen were available in quantity. The remarkable drop in resistance was such as to suggest that if the material could be cooled down to the absolute zero of heat, -273 degrees Celsius, all resistance would disappear and the particular metal would achieve perfect conductivity (note 28). Dewar was very much ‘in’ on all these and on kindred experiments and together he and Fleming wrote some twenty papers recording their findings in this and in other kindred fields.
With Sir William Crookes, James Dewar made several researches on radium investigating the effects of extreme cold on its emanations (note 29). Professor Crookes was intensely interested in radioactivity and had it not been for a prolonged stay in South Africa in 1895 he might have anticipated Rontgen in his discovery of X-rays. Dewar’s collaboration with Crookes was,... NEXT PAGE
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