t
will lower the luminosity.

The non-chemical reader is apt to be confused by the strange names and
their varied terminations, but he need not be when he learns that the
new metals are given names ending in _-um_, such as sodium, cerium,
thorium, and that their oxides (compounds with oxygen, the earths) are
given the termination _-a_, like soda, ceria, thoria. So when he sees a
name ending in _-um_ let him picture to himself a metal, any metal since
they mostly look alike, lead or silver, for example. And when he comes
across a name ending in _-a_ he may imagine a white powder like lime.
Thorium, for instance, is, as its name implies, a metal named after the
thunder god Thor, to whom we dedicate one day in each week, Thursday.
Cerium gets its name from the Roman goddess of agriculture by way of the
asteroid.

The chief sources of the material for the Welsbach burners is monazite,
a glittering yellow sand composed of phosphate of cerium with some 5 per
cent. of thorium. In 1916 the United States imported 2,500,000 pounds of
monazite from Brazil and India, most of which used to go to Germany. In
1895 we got over a million and a half pounds from the Carolinas, but the
foreign sand is richer and cheaper. The price of the salts of the rare
metals fluctuates wildly. In 1895 thorium nitrate sold at $200 a pound;
in 1913 it fell to $2.60, and in 1916 it rose to $8.

Since the monazite contains more cerium than thorium and the mantles
made from it contain more thorium than cerium, there is a superfluity of
cerium. The manufacturers give away a pound of cerium salts with every
purchase of a hundred pounds of thorium salts. It annoyed Welsbach to
see the cerium residues thrown away and accumulating around his mantle
factory, so he set out to find some use for it. He reduced the mixed
earths to a metallic form and found that it gave off a shower of sparks
when scratched. An alloy of cerium with 30 or 35 per cent. of iron
proved the best and was put on the market in the form of automatic
lighters. A big business was soon built up in Austria on the basis of
this obscure chemical element rescued from the dump-heap. The sale of
the cerite lighters in France threatened to upset the finances of the
republic, which derived large revenue from its monopoly of match-making,
so the French Government imposed a tax upon every man who carried one.
American tourists who bought these lighters in Germany used to be much
annoyed at being held up