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And on 10th May 1898 his long campaign was crowned with success. Hydrogen was liquefied. In the course of his research he had built at The Royal Institution a large refrigerating machine for the purpose. His achievement was welcomed with delight by scientists everywhere in the most laudatory terms, Moisson the French chemist called it “a wonder of modern chemistry”. To James Dewar himself it must have brought a feeling of tremendous satisfaction akin to that of Tensing Sherpa and Edmund Hilary when they stood on the summit of Mount Everest (note 21). As Sir William Ramsay, a distinguished contemporary scientist put it. “It is only those who have joined in serious attempts to solve the problems presented by Nature who can understand the exultation which fills the heart at the moment of success. Honours or rewards which may follow are not thought of”. On 1st May 1899 Professor Dewar, when speaking about the work of The Royal Institution, said that having now obtained liquid hydrogen in considerable quantity he “had directly determined its temperature and other physical constants finding its boiling point to be much lower than previously supposed, namely 20 degrees above the zero of absolute temperature and attaining by exhaustion a temperature of only 15 degrees absolute”. He added that pending the discovery of some lighter gas there was no way so far of being able to bridge the gap and reaching the zero point. Professor Dewar also took occasion to issue a warning against the exaggerated accounts of the properties of liquid air which, having originated in America, were now appearing in some popular magazines in Britain. Later in this same year by reaching a still lower temperature, 14 degrees absolute, he achieved the solidification of hydrogen when it appeared as “a clear ice like solid”. It took some considerable further experimental work before liquid hydrogen could be obtained in quantity but by 1901 the obstacles had been overcome and on 13th June of that year five litres of liquid hydrogen were conveyed through the streets of London from Dewar’s laboratory to the rooms of The Royal Society. Now, apart from the limiting condition of the expense involved, it was possible to produce any desired quantity of liquid hydrogen. With the solidification of hydrogen, achieved before the close of the century, it could be said that almost all the known gases were now reduced to liquid and solid form and in this remarkable scientific achievement James Dewar had played a notable part, having, after Moisson had obtained fluorine in the free state, working with Moisson had reduced it to liquid form in 1897. In 1868 Sir Norman Lockyer had suggested that the sun contained a hitherto unknown element which he called helium and which, in 1895, was found also to exist on the earth. This discovery was made by Sir William Ramsay. Helium, “a colourless, odourless and tasteless gas” which was also the lightest of the inert gases was readily obtainable from hot springs. From those at Bath James Dewar obtained supplies but unfortunately they contained neon which froze and blocked the valves. This unfortunate occurrence coupled with the fact that James Dewar suffered a long spell of ill health from 1904 to 1906, resulted in the prize for being the first to solidify helium going to Professor Kammerlingh Onnes of Leyden University who employed a method suggested by James Dewar. On 5th March 1908 Onnes sent a telegram to the British scientist: “Converted helium into solid. Last evaporating parts show considerable vapour pressures as if liquid state is jumped over”. Disappointed though he must have been at being prevented from adding yet another first to his list of successes in the liquefaction and solidification of gases James Dewar, with his customary generosity, telegraphed in reply: “Congratulations! Glad my anticipation of the possibility of the achievement by known methods confirmed. My helium work arrested by ill health but hope to continue later on”. At their meetings that year he described to members of the British Association for the Advancement of Science the apparatus which Onnes had used and pointed out that what he himself had said to them in 1902 with respect to the liquefaction and the solidification of helium had been proved correct. James Dewar had obtained liquid helium boiling at 4.5 degrees absolute and a temperature of 3 degrees absolute had been reached without a sign of solidification. So he had been well on the way to success had circumstances not intervened to hinder him. Now that it was possible to liquefy nearly all the known gases the problem arose as to how they could be preserved in liquid form so that scientists might proceed to further investigation of their properties at liquid temperature and also undertake experiments researching the peculiarities of metals at very low temperatures. Until that problem was solved the labour which had been involved in the liquefaction of gases was of small avail. No scientist could come up with a solution. All were baffled. Dr Morris, who was with Professor Dewar in The Royal Institution at the time, tells how he used all kinds of contraptions to preserve... NEXT PAGE
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