HELIUM—THE SUN GAS

Evening Star, Issue 20995, 8 January 1932, Page 12

HELIUM—THE SUN GAS

ROMANCE OF A RARE ELEMENT First detected by means of a new line in the solar spectrum as an element existing in the sun but undiscovered upon tiie earth, isolated twenty-seven years later from a terrestrial mineral, identified as one of the disintegration fjroducts of . the radium atom, and at ast, after being a scientific curiosity for fifty years, produced in such quantities that it can be used as a filling for the gas bags of airships, such is the romantic history of the element helium. It was in 1868 that Sir Norman Lockyer found a new line in the yellow region of the sun’s spectrum, and since its position indicated that it belonged to none of the elements so far known on the earth, he called the new substance helium, from the Greek word hellos, the sun (writes E.1.R., in the Melbourne ‘Age’). It was soon discovered that this new line, and others that accompanied it, occurred also in the spectra of many of the stars. In 1894 Sir William Ramsay commenced his classical research on the rare gases of the atmosphere, and in that year he discovered argon, the existence of which had been suspected by Cavendish in .’Bs,' and of which there is about 0.8 per cent, in ordinary air. Argon belongs to the group of inert cases, the chief characteristic of which la their failure to enter into chemical combination with *other elements, and it is this inertness which handicapped the early chemists, and enabled argon to escape isolation for so long. The introduction of spectroscopic methods into analytical chemistry greatly strengthened the equipment of the chemist for the study of these gases, for they all have very characteristic spectra, and are readily identified by this means.

Neon, Krypton, and Xenon were also, discovered in the atmosphere by Ramsay during the course of his research, although the quantities present in the air are exceedingly small. The air of a room of average size contains only a quart of neon, the gas which is now an article of commerce, and is used in the tubes of the arresting red neon signs which illuminate the night silhouette of the modern city, and send their beams through the fog to lead homing aircraft to their hangars in the modern airport. Of krypton the same room holds only a thimbleful, and of xenon little more than one of the bubbles in a glass of soda water. Yet all these gases Were detected by Ramsay by the spectroscope, and have been isolated for study from the residue left after the manufacture of oxygen by the liquid air process. Shortly after his discovery of argon Ramsay received a letter from Sir Henry Miers pointing out that the American chemist, Hillebrande, had observed that a considerable quantity of gas, which he thought to be nitrogen, was liberated during the solution of certain minerals. Miers suggested that the gas might prove to be argon, and not nitrogen. Following this suggestion, Ramsay procured a gram of the mineral cleveite at a cost of three shillings and sixpence, and proceeded to purify the gases evolved, and to study their spectra. He observed a number of new lines, and sent a specimen of gas, which he first thought to be krypton, to Sir William Crookes for a- more thorough examination. Crookes’s report was brief: Krypton is helium; come and see it ” ; and so in less than two months from the initial suggestion of Miers the existence of helium on earth had been established,. The importance of this discovery in the field of atomic physics was appreciated later, but in the meanwhile helium took its place as the lightest of the inert gases, and the second lightest, after hydrogen, of all the elements. . . Helium has several characteristics of unusual interest to the chemist. It was the last of all the permanent gases to be liquefied, and for a long time it resisted all attempts to reduce it to the liquid state on account of its very low boiling point—.26Bdeg centigrade, only sdeg above the absolute zero. Even after it had been liquefied by Onens it was found impossible to solidify it, even after it had been cooled to ,272 deg, the lowest temperature ever obtained. Quite recently, however, Keesom, of Leyden, has succeeded in producing solid helium by subjecting the liquid at .269 deg to a pressure of 128 atmospheres. On account of its very low temperature liquid helium has been used in study of the effects of extreme cold on the properties of matter, and some striking results have been secured. It has been found, for instance, that certain metals at these temperatures lose practically all resistance to the passage of electric currents, becoming superconductors. Such investigations have added much valuable information to our knowledge of matter. In 1903 Ramsay and Soddy found that helium was produced in the transformation of radium, and it is probable that most, if not all, terrestrial helium has been produced by the disintegration of radio-active substances. The so-called alpha rays of radium consist of helium atoms, and the helium atom appears to enter into the structure of the nuclei of most ol the elements.

It has been calculated that the energy released in the formation of one pound of helium by radioactive disintegration corresponds to that produced by the complete combustion ot 10,000 tons of coal. It seems likely that under some unknown conditions of heat and pressure in the stars helium is produced from hydrogen, and that it is from complexes built up of the units of hydrogen and helium atoms that the other elements are derived.

Heliuirt' is present in the air to the extent of one part in 185,000 by volume. In the early days the helium required for experimental purposes was produced by heating radioactive minerals, and particularly thorianite from Ceylon, while it was also found that the gases escaping from hot springs often contained appreciable amounts. It was costly to prepare, and seemed likely to remain a laboratory curiosity, although the early experimenters on airships may have looked regretfully on a substance with little less lifting power than hydrogen, which was so completely inert that it would not in-

flame in any possible circumstances at all.

The demand for a safer gas than hydrogen during the war led the Admiralty to initiate an investigation by Professor J. C. M'Lennan into the natural gases which escape from the earth in certain districts of Canada. He found that these contained about 1 per cent, of helium, and a small plant was set up for purifying the helium by removing the other gases by liquefaction. Many thousands _of cubic feet of the gas were so obtained, and were shipped to England in steel cylinders under high pressure. At about the same time the United States Bureau of Mines began an investigation, into the natural gases of Texas, which are rich m helium, and as a result the cost of the gas was reduced until it became possible to use it in place of hydrogen. Natural gases have been found whiefi contain as much as 8 per cent, of helium, and the Helium Company has a plant at Thatcher, Colorado, with a capacity of 600,000 cubic feet of natural gas a day, producing 12,000,000 ft a year of helium. The development of the airship has received a number of setbacks, but even if the lighter-than-air craft does not fulfil all the hopes of its advocates we can bo sure that new and unexpected applications will be found for the helium which we can now produce in such quantities for a few pence per cubic foot. The history of chemistry is full of the rapid adaptation of new materials to the needs of mankind, and doubtless the sun gas is destined to take its place among the useful products of Nature’s laboratories in the depths of the earth.