GUARDING A FORTUNE

Timaru Herald, Volume CXXXVII, Issue 19314, 15 October 1932, Page 2

GUARDING A FORTUNE

RADIUM IN COMMONWEALTH LABORATORY.

Below the level of the ground near the main quadrangle of the University of Melbourne is the Commonwealth radium laboratory, in which is kept that part of the 10 grammes of radium purchased some years ago by the Federal Government, which is not on loan to the hospitals of Australia. Occupying only two small rooms, the laboratory, in proportion to its size, is probably the most interesting, and in one respect certainly the most dangerous, place in the whole of the University. Comparatively few persons know of its existence. There is seldom more than one gramme of radium in the laboratory, and of this about half is kept constantly dissolved in a protected bottle of chemicals. The part which is not dissolved does not impress the visitor. It is in small metal .containers, made in the form of needles, heavier diameter tubes, or “plates,” resembling the smallest weights used on letter scales. All the containers are made of platinum, and the radium is hermetically sealed inside. From the tiny spot of radium in the heart of each container there flows out through the platinum casing a constant stream of rays of two kinds. One is a radiation similar to light rays or wireless rays, but is much shorter in wave length than the shortest light waves, and is therefore invisible. Actually it is a form of X-ray, but it is much more penetrating. It radiates into the air for hundreds of feet about the tube, and constant exposure to its influence would result in destruction of the tissues of the body, and ultimately death. The second radiation which comes through the tube is really a shower of minute electric particles, so small and travelling so fast that the majority of them are propelled through the metal of the tube and far into the air. Radium is constantly giving off a third kind of radiation consisting of particles of the gas known as helium, which is used for inflating airships, but the helium particles do not travel sufficiently fast to penetrate the platinum casing of the radium. Constant Disintegration. Those who recall that the Federal Ministry paid £IO,OOO a gramme for its supply of radium may be concerned to hear that this valuable asset is slowly changing into lead. Radium is an unstable substances, and the radiations which is gives off are merely a manifestation of the fact that it is becoming something more stable. Radium does not, however, change directly into lead. It becomes lead only after it has changed successively into several other substances, all of which are radioactive, and some of which are even less ' stable than radium. The rate of the : disintegration of radium is such that at the end of every 2000 years the quantity of radium in any container will be only half as great as the quantity which was there at the beginning. When a particle of radium breaks up, and gives off the three forms of radiation, the place of the particle of radium is taken by a particle of a very radio-active gas called radon. This gas possesses all the’ useful properties of radium, but half of its substance will disintegrate in four days. It is with the radon that the routine work of the Commonwealth radium laboratory is mainly concerned. Radon can be used in the treatment of hospital patients. The radium laboratory collects the radon released from its bottle of dissolved radium, and supplies it to the hospitals. The process of collecting the radon is complex, partly because the amount released from the radium solution is minute, and partly because the radium is constantly breaking up the water in which it is disssolved into its two constituent} gases—oxygen and hydrogen—which considerably exceed the volume of radon released, and which are mixed with it. Thus, it is necessary to separate the radon from the other gases. This is dope partly by chemical means. The final process is the cooling of the mixed gases with liquefied air. Subjected to the intense cold at which air becomes a fluid, the radon gas collapses into a semi-solid substance, but the oxygen and hydrogen retain their gaseous properties, and are removed with a pump. Then the radon is allowed to evaporate back into a gas, and it is “bottled” for the hospitals. Bottles of Gold. Connected to the apparatus in which the radon is collected is a tube about 3ft in length made of pure gold. This tube is no thicker than a piece of string, and its walls are about twice as trick as the tiny central bore which is filled with radon. The tube is filled by sealing one end. connecting the other to the radon container while 'the radon is still frozen solid by the.liquid air, and withdrawing the air from the tube. Then, when the radon evaporates, it flows into the evacuated tube. By merely pinehing the tube it can be sealed and withdrawn from the gas collector. Owing to the varying quantity of gas collected from day to day the strength of the radon imprisoned in the gold tube varies, but for hospital work it is essential that the dose applied should be of known strength. The strength of .the radop in a given length of the gold tube is gauged by measuring electrically the strength of the radiations given off, and, when the strength of radon in, say, one centimeter of the tubing is measured, it is easy for the experts to obtain a dose of the correct strength simply by calculating the number of centimeters of tube necessary to provide it. The three feet of tube is therefore cut up into shorter, carefully measured sections. These sections are then enclosed in nickel sheaths, or needles, to each of which a thread is attached to facilitate handling, and are distributed to the hospitals in accordance with their orders. Protection of Laboratory. Because of the disastrous effects of the radium radiations on persons constantly exposed tp them, elaborate precautions ate taken to protect the workers in the laboratory. The safe contaijiipg the radium extends far under the ground. The heavy steel of which it is made is lined inside with 6in. of lead. Even this does not completely stop the radiations; but it weakens them sufficiently to render them harmless. The laboratory is equipped with a powerful farced ventilating system by which the air is changed twice a minute. Should the delicate glass tubes comprising the apparatus in which the radon is collected be broken, the gas would be released into the laboratory. The workers would then have to retreat immediately, and remain outside the building until the ventilators had completely removed the gas. Radium equipment is handled behind lead shields, 3in. thick, designed to protect the workers’ bodies. Wooden pincers are used instead of steel ones for handling material, because radium rays, which strike metal drive electric particles out of it, and these would bombard the hands of a person using metal tools, and injure the tissues of the flesh.

The director of the laboratory (Mr A. H. Turner) and his assistants consider that their most valuable safeguard consists merely of a tiny slip

of unexposed photographic film, which they always carry in a light case in their vest pockets. Penetrating the clothing and the case carrying the film the radium rays produce upon the (iln> the sgme effect as light. Thus, when the film is developed at the end of each week, it is possible to see immediately from the amount of fogging upon it how much the person wearing it has been exposed to the rays, and if necessary to provide immediate additional safeguards. So valuable has this simple device proved that Mr Turner is now engaged upon the preparation of plans for protecting all the radium and X-ray workers in hospitals by means of similar films.