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liquid air or oxygen in quantities from day to day. Boxes containing powdered cork, hay or crumpled newspapers were used in vain attempts to reduce the evaporation of these cold liquids. On one occasion Dewar pressed Lady Dewar’s hat box into service. But in spite of all his endeavours nothing was left of the cold liquid next morning. All had evaporated. Then, reflecting on his work with high vacua during his Edinburgh years (note 22) and on the effectiveness of charcoal in absorbing gases and in particular on how coconut charcoal, if reduced to a very low temperature, was an effective agent for this purpose James Dewar by using a vacuum to jacket the glass vessel containing the cold liquid met with success. The distance between the walls needed to be only two or three millimetres with internal silvering of the vacuum space. Thus the sphinx-like riddle was solved. The use of low temperature charcoal made it possible to use metals such as brass, copper or nickel instead of glass for the construction of double jacketed vessels which contributed greatly to solving the problem of the safe storage and the transportation of liquid air and oxygen for, in the long run, industrial and domestic uses. It was now Professor Onnes’s turn to offer congratulations to James Dewar, which in the true spirit of science he did handsomely in a speech in 1904 when he spoke of “Dewar’s magnificent invention, which may be called the most important appliance for operating at extremely low temperatures”, adding that “the moment when a vacuum glass containing liquid oxygen was offered to the Prince of Wales at a meeting of The Royal Institution marks an era in low temperature research”. For James Dewar the production of liquid gases was not an end in itself but a means to opening up further novel methods of research in which he was now to engage vigorously not only on his own but in collaboration with many other scientists in their specific fields of enquiry. Had he patented his invention of the vacuum flask James Dewar would have made an immense fortune but he was no Mr Worldly Wiseman in matters of finance. Like his great master, Faraday, “he loved the labour better than the wage” and it was left to a German firm to cash in on his great discovery and to develop and market that vacuum flask which, like the Waverley pen, “came as a boon and a blessing to men”. At first, the small quantities of liquid gases which were available restricted his range of investigation, confining him to determining the properties of the liquids themselves but by the late nineties when these gases – air, oxygen and hydrogen – became more plentiful in liquid form and later could be preserved for indefinite periods as such, by using his invention of vacuum jacketed vessels, the range for experimentation was greatly widened. Before recounting these and his engagements with other experts in various fields we must now turn back the pages of his life and mention some of the other events in which he participated.
As one would expect James Dewar joined The Chemical Society early in his career, was a regular attender at its meetings and took part frequently in its discussions. He served as a member of its Council from 1884-1886 and was thrice appointed one of its vice-presidents. His nomination to its presidency caused some discussion, a very rare occurrence in that Society. This was due, in part, to the fact that some members though that although he had scrupulously performed the duties incumbent upon him, he had devoted less time than he might have done to the responsibilities of his Chair in Cambridge University and in part also to his rather brusque manner at times which offended some of his fellow members. A rival candidate, in the person of Sir William Ramsay, was nominated. The result of the election was in James Dewar’s favour by 166 votes to 152. Characteristically he showed no resentment at there having been a contest and was as courteous and friendly to his opponents as to his supporters. Indeed, such was the excellent way in which he discharged the duties of his office as President that many who had voted against him said that they regretted having done so. During his presidency a Banquet was given in honour of the past presidents who had completed fifty years membership of The Society (note 23) at which Professor Friedel of France, one of the many overseas guests, remarked that “there was present the finest phalanx of the Fathers of our Science which exists in this country”. Professor Dewar had but one regret. It was that his beloved teacher Lord Playfair had died shortly before the event. During James Dewar’s period of office the Journal of the Society was overhauled and a collective index, so necessary for those who wished to pinpoint particular items in past numbers was prepared by Mrs Dougal who had been appointed indexer. It was remarked too by the members that for the first time in many years the Journal appeared in print on the due date and not belatedly, even by several months, as had been happening in previous years. This was brought about... NEXT PAGE
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