"You remember that gold is usually found in small grains in the midst of certain rocks. The rock is crushed up very fine, and then mixed with mercury. It is a curious property of mercury that it will at once unite with other metals if it is mixed up with them.
"The mercury in this case seizes upon the little grains of gold, but will not unite with the earthy partsof the ore. The earthy parts are carefully washed away in shallow troughs leaving the heavier metallic grains behind.
"These are easily collected, and all that remains is to heat them gently. The mercury flies off in vapor with the heat, and is condensed and collected for further use. The grains of gold remain behind.
"Mercury is also used for "silvering" the backs of looking-glasses, and for various other purposes."SUMMARY
The ore from which mercury is obtained is a rough, brown stone, called cinnabar. It contains, besides the metal, a large quantity of sulphur. It is broken up into small pieces and heated, and the sulphur passes away in vapor, leaving the liquid metal behind.
Lesson 25
The Frog
"Come and see what we"ve got, Norah," said Fred. "Oh, you dreadful boys," said Norah. "It"s a nasty,ugly frog. I don"t like frogs."
