St Ignatius College - Ignatian Yearbook (San Francisco, CA)

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RADIO-ACTIVE SUBSTANCES 27 RADIUM. Radium is the only new radio-element that has so far been isolated in the form of pure compounds, or which has been found to give a new spectrum. The quantities of pure ra- dium compounds obtained are excessively small. Only a few tenths of a gram of radium chloride can be extracted from a ton of pitchblende, and this is in the ratio of one part to several millions of the original mineral. On the other hand, the radio-activity of the pure compound is correspond- ingly increased, and the tiny quantity extracted from a ton of ore retains in concentrated form the greater part of the radio-activity of the original mineral. Wleiglit for weight, the radium compounds are at least a million times more active than the compounds of uranium and thorium. The atomic weight of radium is 225 which places it in the position of the third heaviest element known, the two heavier being the other radio-elements-thorium 232 and uranium 238. SOURCE AND METHOD or EXTRACTION. , Radium is now obtained chiefly from carnotite, though a small amount is derived from pitchblende. Practically all of the world's radium until nine years ago, came from de- posits in Portugal. The first important radium operations in the United States did not commence until 1912, although a small plant designed to recover uranium from earnotite ore was erected in Colorado in 1900. The following method of the treatment of radium extrac- tion has been taken from Madame Curie's Thesis on the subject :-To extract the uranium, the ore is roasted with so- dium earbonate, lixiviated with warm water and then with dilute sulphuric acid, when the uranium passes into solution. The insoluble part consists of the sulphates of lead and cal- cium, alumina, silica and iron oxide, together with greater or less quantities of nearly all the metals. These residues pos- sess an activity four and one-half times that of uranium, and constitute the raw material used for the extraction of radium.

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26 THE IGNATIAN spontaneously give out heat and other manifestations of en- ergy which are able to affect a photographifl Plate? to Cause certain substances to fluoresceg and to render the air in their neighborhood a conductor of electricity. These other mani- festations of energy are called rays, and from this comes the term radio-activity. Three different kinds of these rays are distinguished, the alpha, beta, and 'gamma rays. The alpha rays are responsible for most of the ionization of the air produced by radio-active substances, they can penetrate the air only a few centimeters and are easily stopped by paper. They are connected with the development of the greater part of the heat evolved by such substances. Vtfhen uniniiuenccd by external forces they move in straight lines, but under the influence of an electrostatic or a mag- netic field, they are slightly bent out of their path and act as though they consisted of a. stream of rapidly moving particles charged with positive electricity. The beta rays are more penetrating than the alpha rays and pass readily through paper and even through thin sheets of metal. They are especially active toward a photographic plate. Like the alpha rays they move in a straight line, un- less influenced by a magnetic or electrostatic field when they are deflected in the opposite direction from that in which the alphas are turned, and much more strongly. The gamma rays are characterized by extraordinarily great penetrating power, being able to pass through bodies which will stop the other forms of radiations. No deviation of these rays has been detected in the most powerful magnetic fields it is possible to obtain, and in this respect they are more nearly allied to the X-rays than to the alpha and beta rays, but in their absorption by different kinds of matter they exhibit an almost complete parallelism to the beta rays. Their effects are insignificant compared with that of the other two types.

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28 THE IGNATIAN The insoluble sulphates are converted into carbonates by boiling with a concentrated solution of carbonate of soda, and the soluble sodium sulphate produced is removed by repeated washing. The residue is treated with hydrochloric acid, which dissolves most of it, including the polonium and actin- ium, but the radium remains undissolved, as unconverted sul- phate. It is Washed with Water, again boiled with concen- trated sodium carbonate Cwhich completes' the transforma- tion of the sulphates into carbonatesj, again thoroughly washed, and then treated with dilute hydrochloric acid free from sulphuric acid. Polonium and actinium are still pres- ent in the solution, from which the radium and barium are removed by precipitating with sulphuric acid. From 1 ton of residues l0kg. to 20kg. of crude sulphates are thus obtained. of activity about sixty times that of uranium, and these con- tain calcium. lead, iron and a trace of actinium. The sul- phatcs are transformed into chlorides as before, and the solu- tion treated with sulphuretted hydrogen, filtered, oxidised with chlorine and precipitated with ammonia. The activity of the precipitated liydrates and oxides is due to actinium. The filtrate is precipitated with sodium carbonate, and the precipitate washed and converted into chlorides, evaporated to dryness, and the chlorides washed with concentrated hy- drochloric acid, which removes calcium. The purified chlor- ides of barium and radium thus obtained possess an activity of about 60. Eight kilos are obtained from 1 ton of residues. At this stage the material leaves the factory, and is now frac- tionated in the laboratory. PRACTICAL USES or RADIUM. Apart from its role of importance in the world of science, radium is today, recognized as a tremendous factor in the world of medicine and industry. The medical fraternity has come to accept radium as a beneficial treatment for cancer. Permanent cures have been accomplished, and practically every large city has at least one hospital that is supplied with a small quantity of radium. In actual practice the surgeon