Incandescent gas mantles

Cerium is a component of misch metal, which is extensively used in the manufacture of pyrophoric alloys for cigarette lighters. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. The oxide is an important constituent of incandescent gas mantles and is emerging as a hydrocarbon catalyst in self cleaning ovens. In this application it can be incorporated into oven walls to prevent the collection of cooking residues. 

Cerium(lll) chloride is used to prepare cerium metal and other cerium salts. It also is used as a catalyst in olefin polymerization, and in incandescent gas mantles. 

Thorium nitrate is a reagent for measuring fluorine and for making thori-ated tungsten filaments. Thorium nitrate containing 1% cerium nitrate is the impregnating liquid in making incandescent gas mantles. 

Origins. Since the 1890 S, monazite, the first commercial rare earth ore, was mined from black beach sands in Brazil and shipped to Austria for its 5 to 10% thorium oxide content. Carl Freiherr Auer von Welsbach spent 20 years of research work developing a bright incandescent gas mantle he discovered in 1866 with... 

Baron Auer is best remembered for his invention of the incandescent gas mantle, a truly great advance in the history of illumination (55). Instead of attempting to produce a gas which would bum with a luminous flame, he decided to use a non-luminous flame to heat a refractory mantle to incandescence. The problem, as he said, "was not to find a process by which an infusible compound could be given a definite shape. This invention is founded, above all, on the fact, proved by numerous experi-... 

Th02, is a white solid that adopts the fluorite structure (as do the MO2 phases of the other actinides). When heated it gives off a rather bluish light if about 1% cerium is added, the light is both whiter and more intense so that the mixture came to be used in making incandescent gas mantles, widely used for lighting until comparatively recently. 

Use Incandescent gas mantles, spectrography, preparation of cerium metal, polymerization catalyst. 

Uses. — Pure metallic cerium has no commercial uses, but its alloys are both interesting and capable of wide application. The most important of these is the alloy called misch metal, mixed metal, commercial cerium, or simply cerium, It is essentially a mixture of cerium, lanthanum, neodymium, and praseodymium, but as usually prepared it contains from 1-5 per cent iron and very small amounts of other elements. The most abundant constituent is cerium, which sometimes runs as high as 70 per cent or more, though generally it is about half of the mixture. The alloy is produced from the rare earth residues of monazite sand. This mineral is used in large quantities for the manufacture of incandescent gas mantles (see Thorium Uses), which usually contain 99 per cent thoria and 1 per cent ceria. The composition of various monazites is shown in Table XXVI. 

The only important commercial use of thorium, however, is in the manufacture of incandescent gas mantles. This industry had a very modest beginning in 1884 when Welsbach patented the use of a fibrous network of rare earth oxides which were to be heated by an ordinary gas flame of the Bunsen type. The first mantles were composed of a mixture of zirconia, lanthana,... 

The various chemical extraction stages from ore to metal are discussed some of the intermediates arising from these stages have major industrial uses or potential uses of their own. Pure thorium oxide, for example, has been employed for many years in the manufacture of incandescent gas mantles and this is at present probably still the major outlet for thorium in any form. It is antidpated that new uses will be found for most of these metals or their pure intermediates in the near future and as a result many of the process stages described will achieve a wider application. 

Incandescent gas mantle (Carl Auer von Welsbach) The Austrian scientist invents the incandescent gas mantle. 

White Th02 is made by thermal decomposition of Th(ox)2 or Th(N03)4 and adopts a Cap2 structure (Fig. 6.19). It is precipitated in neutral or even weakly acidic solution. Nowadays, Th02 has application as a Fischer-Tropsch catalyst, but historically, its property of emitting a blue glow when heated led to its use in incandescent gas mantles. As expected from the high formal charge on the metal centre, aqueous solutions of Th(lV) salts contain... 

The use of consumer products that contain radioactive sources can contribute to nonoccupational exposures (320). Examples of consumer products incorporating radioactive materials are radioluminescent indicators (timepieces, signs, instrument dials), ionization smoke detectors, anti-static devices, dentistry porcelains, pottery glazes, incandescent gas mantles, and tobacco products. Low levels of radiation are also generated by such sources as color television tubes, but emissions are well controlled and the glass of the picture tube is sufficiently thick to absorb most of this radiation. 

Welsbach s incandescent gas mantle patented in 1885 enabled the gas industry to compete for a few more decades with electric lights. 

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