RADIUM

Hokitika Guardian, 16 January 1929, Page 2

RADIUM

HOW IT IS BOUGHT. VALUE .UKASL'KKD UV ACTIVITY: CONTAINKRS LIKE NK FOLKS. (London Daily Mail.) Buying ;i gramme of radium. even ?f you have tlie necessary money, is by no moans such ;i simple mutter us the purchase of u LTIkOUO peurl ueckluce, though the cost is uhout equal. In the first place- it is not weighed. Its value depends upon its “radioactivity,” and this must he measured. This delicate task is always entrusted to some impartial scientific institution, such as the National l’hysicial Laboratory.

A sensitive instrument known as an electroscope, which reacts to the oamma rays of radium, is used. It is surrounded by lead screens, which shut out all other rays, and by comparing the effect of the sample to he measured with a standard amount placed at the same distance, its quantity can be calculated to within onehundredth of a milligramme. A still more delicate test, the “emanation method,” will detect and measure the presence of radium in ores or minerals in amounts of 1-1.000,000.-000,0001 hs of a milligramme, but is not necessary for practical purposes.

GRAINS WORTH THOUSANDS

The few grains of sandy, brownish, powder, which are all that appears to the naked eye in a sample of radium sulphate worth many thousands of pounds, cannot, for obvious reasons, bo allowed to bo about loose. They are hermetically enclosed with gold solder in platinum containers. These may he of many different shapes or sizes, according to the clinical purpose for wliiclr they are required, and are usually made to the .specification of the purchaser. Some are very much like ail-ordinary sewing needle, either biunt-oiided or with a sharp triangular point to enable them to be buried deep in malignant growths. A tiny cavity, like the bore of a rifle barrel, runs down the centre of them as a receptacle for the radium. An eye at the outei end. through which a thread can be passed, minimises the risk of loss.

AYII ERE IT COMES FROM

For surface application, Hat containers fitted with brass, silver, or aluminium filters, by which those rays which are not wanted are absorbed, arc used. Very small quantities are sometime:* sealed into tiny platinum cylinders, and a varying number of these can be placed, as required, into a silver-gilt outer tube, or into the hollow of an empty platinum needle. ■ Although the making o'f these delicate containers necessarily takes some little time, there is no undue delay onee the customer lias made up his mind upon what type ajid size will best suit his special requirements.. A small amount of vadium is mined in Australia, but the bulk of it comes from the Belgian Congo, whore it is found in pitch-blende ores, in company with cobalt, copper, and other metals. The mines in Colorado, owing to their small content, cannot now be worked at a profit.