CHAPTER XXX THE RADIUM MINE OF ST. IVES OR some fifty years past on the near outskirts of St. FOR Ives has stood an ugly heap of refuse and debris, an eyesore to the numerous artists of the town and a nuisance to the neighbourhood generally. No one guessed even in his sanest intervals that in this refuse heap lay an element worth perhaps a hundred times as much as an equal quantity of auriferous rock from the Rand. This refuse contains a substance called pitch-blende, from which the marvellously active and valuable radium is extracted. Pitch-blende is in appearance like solidified tar, and is a very rare substance. A small quantity has been found at Nogent-sur-Marne, in France, and at the Joachimsthal Mines in Bohemia, eleven miles from Carlsbad. It occurs here at the old Trenwith Mine, and at one other spot only in Cornwall so far as is yet known. The geologist Henwood so far back as 1843 called the attention of scientists to this pitch-blende at the Trenwith Mine, concerning which he wrote: "Pitch-blende (oxide of uranium) occurs in great abundance among the copper ores of Wheal Trenwith, and was long carefully collected and thought to be black copper ore. The low prices obtained for the ores with which it was mixed, and the inferiority of the metal they yielded, equally disappointed the miner and the copper-smelter, until a specimen of the copper was examined by Mr. Mitchell, of Calenick, and found mixed with titanium in a metallic state. The ores were then inspected, and, pitch-blende being discovered among them, its nature and prejudice to the copper ores were explained to the workmen, by whom it has been, of course, since rejected. Was there ever an instance in which an acquaintance with mineralogy and chemistry would have been more useful?" Since 1856 no work has been done at the Trenwith Mine, but now a syndicate has been formed to extract radium from the refuse. So the discovery of a lady, Mme. Curiefor it was she, and not her husband, who discovered radium -may bring back mining prosperity to St. Ives. Mr. Francis Darwin, when President of the British Association, a few years ago, pointed out that radium was millions of times more powerful than dynamite, and that there was enough energy in a pound and a half to drive a cruiser six thousand miles at high speed. The whole story of radium reads like a delightful fanciful tale from the Arabian Nights. The practical applications of radium, when sufficient of it is obtained-and the demand will, no doubt, as was the case with aluminium and other elements, make the desired supply-are almost beyond the wildest dreams of youth. The market value of radium is almost impossible to be estimated. It is said by the experts that the pitch-blende at the Trenwith Mine will yield about one and one-hundredth grains to the ton. This quantity, in size only that of a small pin's head, is worth probably between £1000 and £1500. Marking such an epoch in the mining industry of Cornwall, it is not without interest to know something of the spot which has already aroused so great an interest not only locally, but all over England. 66 According to Domesday Book "Trenwit" was owned in the time of Edward the Confessor by Sitric the Abbot, and before by the Earl of Cornwall and his Villeins." In the Exeter Domesday this manor is called "Trenuwit.' Trenwith was granted to John de Beaufort, son of John of Gaunt, by the Earl, and continued in his family till the attainder of Edmund Beaufort, Earl of Somerset, in 1471. Since then the manor seems to have been annihilated. The barton some time previous to the reign of Edward IV became the property of a family called Bailiff, who then took the surname of Trenwith. The Trenwith family died out by the death of Rebecca Trenwith in 1798. 66 Trenwith means the habitation by the trees," the early form of it being "Treunwyth." In looking through the parish register one sees that the common baptismal name in this family, which descended from father to son for many generations, was "Renatus." It would be interesting to know how this remarkable Christian name originated. I visited the famous Trenwith Mine, being kindly shown over it by Mr. T. J. Chellew. It is close to and immediately above the town. At the time of my visit men were at work putting a fine electric pump into one of the shafts for clearing the water from the workings. Immense heaps of debris, in the form of broken-up pieces of ore dull reddish in colour when seen in masses, lie around on the slopes, from which the town and church of St. Ives are scarcely divided by any tangible interval. You could throw stones from the top of the heaps on to the roofs of the houses below. Men with spades and hand-barrow were painstakingly sorting out and picking over the debris on the look-out for pitchblende-a blackish, vitreous substance-a little like pitch, containing the oxide of uranium in thin silvery streaks. These streaks run not in straight paths, but zigzag and turn about here and there in the pitch-blende heavy lumps, for very heavy is uranium. There are several grades of the ore, with varying richness in the uranium salt. At present (1909) the pitch-blende is obtained solely from the debris of the workings of the old Trenwith Mine, which closed down some forty years ago. When the electric pump is working and the water has been cleared out from the mine's interior, search will be made for pitch-blende, which will be won and brought to the surface. The mine-water has great radio-activity, so that probably pitch-blende exists there in some quantity at least-in what quantity time will prove. If in large quantities, the gold and diamond mines of the world must take a distinct back seat as moneymakers. Radium, of course, is not seen actually at the Trenwith Mine. What one does see is this uranium oxide in the pitch-blende, from which by processes in the chemical laboratory the salts of radium are extracted. At the head of the Trenwith Mine are several locked sheds, in which the precious pieces of pitch-blende are secured under lock and key. As the pieces are discovered by the workmen picking over the debris, they are at once dropped between bars into locked boxes. These precautions are necessary. Let me mention one significant fact. Two small parcels of pitch-blende were sent to Germany, and were both lost on the road! There is a fully equipped chemical laboratory at the mine, where necessary tests, experiments, and analyses can be conducted. Should it eventually happen that pitch-blende rich in radium be found, St. Ives will become the most important place in Europe. The eyes of all nations, and particularly the war departments of the world, are very closely watching the progress of the advent of this latest scientific marvel. The known quantity of pitch-blende in the world is extremely limited. Though uranium is found in other ores, it is not commercially available. Therefore, so far as is known at present, pitch-blende is the only practical source of radium. The presence of radium causes one to take precautions which are quite unusual. I took my charged camera into one of the little houses where the pitch-blende is stored, and suddenly remembering the wonderfully actinic potency of the emanations from the ore, rushed out and deposited my camera outside, for the rays treat wood, leather, and metal almost as if they were not. When radium comes into general use it will make us careful in many directions where we are not at present, and will lead to many revolutionary customs and usages. Sir Joseph Thomson, at the meeting of the British Association at Winnipeg (1909), said some pertinent words about radium. He is of opinion that the most plausible theory of radio-active energy is that the elements are not permanent, but are gradually breaking up into elements of lower atomic weight: uranium, for example, is slowly breaking up, one of the products being radium, which radium itself breaks up into a radio-active gas called radium emanation, the emanation into another radio-active substance, and so on. The radiations, in short, are a kind of swan's song emitted by the atoms when they pass from one form to another. Thus, when a radium atom breaks up and an atom of the emanation appears, the rays which constitute the radio-activity are produced. The atoms of the radio-active elements are, then, not immortal ; they perish after a life whose average length ranges from RADIUM SEQUENCES 305 thousands or millions of years in the case of uranium to a second or so in the case of the gaseous emanation from actinium. The energy developed by radio-active substances is exceedingly great. One gramme of radium develops nearly as much energy as would be produced by burning a ton of coal. One indirect effect of the discovery of radium is the light it throws upon the age of the earth. Before the discovery of radium it was supposed that the supplies of heat furnished by chemical changes going on in the earth were quite insignificant. It was thought that the heat of the earth in the interior was gradually going, and nothing could replace it; that when the earth first solidified it only possessed a certain amount of heat, which it is constantly spending, and not gaining fresh heat. Though the quantity of radium in the earth is an exceedingly small fraction of the total mass, yet the total amount of heat given out by this small quantity of radium is so great that it is more than enough to replace the heat which flows from the inside to the crust of the earth. If radium behaves in the interior of the earth as it does at the surface, rocks similar to those in the earth's crust cannot extend to a depth of more than forty-five miles below the surface. Though the discovery of radioactivity has thus taken away one method of estimating the earth's age, it has supplied another. The gas helium is given out by radio-active bodies, and since it is not found in minerals which do not contain radio-active elements, it is probable that all the helium has come from these elements. In the case of a mineral containing uraniumthe parent of radium in radio-active equilibrium, with radium and its products, helium will be produced at a definite rate. Helium is permanent and accumulates in the mineral. Hence, if the amount of helium in a sample of rock be measured, and the amount produced by the sample in one year, the length of time the helium has been accumulating, so the length of the age of the rock can be determined. But the most interesting feature about this latest scientific marvel, radium, lies in its suggestiveness. Middle-aged scientific men remember that it was not unusual for quite a pessimistic feeling to be prevalent: that all the interesting |