DISCOVERY 



143 



which are imbued with a perfectly miraculous elas- 

 ticity. 



To supply this demand for vanadium, an entirely 

 new source was discovered in the camotite beds on 

 the borders of Utah and Colorado. This mineral is 

 little more than an impregnated sandstone ; and 

 though it is excavated in enormous quantities primarily 

 for the vanadium it contains, it gives rise to a waste- 

 product more valuable than the vanadium itself. 

 This is uranium, another rare metal, which in its turn 

 yields yet another rarer than itself, the famous radium, 

 which caused such a sensation a few years ago, when 

 Madame Curie succeeded in isolating it from many 

 tons of pitch-blende. It remains to-day the most 

 costly of all the rare metals, though in this respect 

 the metal platinum needs some beating, being worth 

 more than £40 per ounce to-day, whereas a century 

 ago an ounce could be bought for a few shillings. 

 The reason for this enormous rise in its price is due 

 to the actual rarity of the metal and the manifold 

 uses to which it can be put. The family to which 

 this metal belongs is a very select one comprising 

 but si.x members. Of these metallic aristocrats the 

 best known are palladium and iridium ; the latter 

 being familiar to most users of fountain-pens, for it 

 is from this metal that the points of the gold nibs 

 are made, together with another member of the same 

 family, osmium, which is alloyed with it. Palladium 

 has received a good deal of attention during the war 

 as a possible substitute for the prohibited platinum, 

 the stores of which had to be reserved for a multitude 

 of national needs, where it was not possible to use 

 another metal. Palladium has been used with some 

 success in the jeweller's art, though it does not possess 

 the unique properties of the nobler metal. The 

 Platinotype Co. have, however, produced a palladio 

 pa{>er which is in every way the equal of, if not superior 

 to, the well-known platinotype papers. 



This search for a substitute for platinum has led 

 to the development of another rare metal, tantalum, 

 which has been used with great success for making 

 dental instruments, being very hard, easUy sterilised, 

 and not subject to rust. In tantalum we have a 

 metal of which there is plenty to be had, and for which 

 as yet but little use has been found. We have edready 

 seen how the Germans, in their search for a cheap 

 source of thorium, discovered monazite in Brazil. 

 This country is the home of yet another rare metal 

 which has had quite a vogue during the last few years. 

 This is zirconium, which occurs in huge quantities 

 in the mineral brazilite, which is almost pure zirconium 

 oxide, from which it is not difficult to obtain the pure 

 material. This is sold under the proprietary name 

 Zircite. It is now being used in ever-increasing 

 quantities as a refractory substance for the manufacture 



of crucibles, furnaces, and other articles which are 

 required to withstand the high temperatures which 

 are now so easily attained with modern electrical 

 contrivances. Another rather interesting use to which 

 the oxide of this metal has recently been put, chiefly 

 in America, is as a cheap substitute for the expensive 

 bismuth carbonate used in medicine for making 

 X-ray photographs. Zirconium, moreover, finds many 

 other uses in the steel industry and in the drawn 

 filament electric lamps. Combined with yttrium, 

 yet another rare metal, belonging to the family of 

 the rare earths, it is used in the manufacture of the 

 Nemst lamps, formerly much in evidence in physical 

 laboratories. It also finds a special use in the Bleriot 

 automobile head-lights. Zirconium is typical of a 

 case where, given the material, uses will quickly be 

 found for it should it possess particular properties. 

 There are two or three rare metals for which as 

 yet no use has been found, cither because they possess 

 no very distinctive property, or perhaps because they 

 really only exist in very small quantities : who can 

 say ? Time alone will answer this question. Of these 

 germanium, gallium, and indium may be mentioned 

 here ; and they are interesting from another point of 

 view as being illustrative of the way in which a new 

 metal is discovered. This may happen in several 

 ways ; more often than not the chemist stumbles 

 across a new metal when least expecting it, or he 

 may set out more or less deliberately in search of one 

 the existence of which has been predicted. Gallium 

 and germanium are instances of the latter course ; 

 they were both predicted by the Russian chemist 

 Mendeleeff by means of his great discovery the 

 " Periodic Law." It was in 1875 that Lecoq de 

 Boisbaudran discovered gallium in a blende from the 

 Pyrenees, after an extensive spectroscopic examination 

 of many minerals. Germanium came to light ten 

 years later, when Winkler was making an analysis 

 of a new silver mineral and found there was a uniform 

 shortage of 7 per cent, in his analysis, which led him 

 to suspect the presence of some unknown metal. 



Indium, on the other hand, is an example of the 

 accidental method. In 1861 Reich and Richter were 

 examining two Freiberg blendes for the rare metal 

 thallium, discovered by Sir William Crookes two years 

 earlier ; they failed to detect it by means of the spec- 

 troscope, but were rewarded by discerning the lines 

 of an unknown metal which they named indium. 

 Thallium is an example of a very rare element having 

 found a use, owing to a peculiar property possessed 

 by it alone, namely the brilliance and high refractive 

 power it imparts to glass, making it particularly 

 suitable for optical work. A source of supply sufficient 

 for this purpose was found in the flue-dust of those 

 pyrites burners where ore containing thallium was burnt. 



