"What is that, Professor?"
"It is a very fine sample of Cinnabar."
"I never heard of it before. What is it used for?"
"It is the ore from which quicksilver, or mercury, is extracted."
"Wouldn't it be fun to make a looking glass?"
"It is used for that purpose, but we have use for it in making a thermometer, as well as a barometer," answered the Professor.
"Will it be much trouble to take the quicksilver out of the ore?"
"No, it is a very simple process. Metallic mercury is easily volatilized, and separated from the gangue, at temperatures far below redness. Our closed retort would be admirable for the purpose."
"Do you mean by volatilizing that it is put into a steam?"
"Volatilizing means to convert it into a gas, and this gas, on coming into contact with a cooling surface, is converted into a mercury, which we have in a liquid state, and is called the metallic mercury."