NATIVE COPPER.
Copper is a reddish-coloured heavy metal, much used for sheathing the under part of ships, for making boilers, &c. It is about eight-and-a-half times heavier than water, and is too valuable to be used for many purposes where either iron, tinned iron, or zinc are applied, but for which purposes its great durability would fit it, as it is easily rolled out or beaten into plates, and is not quickly acted on by the weather. It is used as coin in pence, halfpence, and farthings; all vessels for cooking purposes, when made of copper, are tinned inside to prevent the food becoming poisonous from verdigris, which is the rust of copper, and is very injurious. Copper is found chiefly combined with sulphur, forming “native sulphuret of copper.” Copper melts at a full red heat.
LEAD.
SULPHURET OF LEAD.
Lead is a heavy metal, of a dull blueish tint, and very soft; it is extensively used for covering roofs, for cisterns, and for pipes for conveying water, as it is easily bent and joined, and is not acted on by the water which passes through it. Lead melts at a heat below that of redness, and, in combination with oxygen and carbonic acid, forms the “white lead” of commerce so largely used as a paint. Oxide of lead, called “litharge,” enters into the composition of flint glass, and in combination with a larger quantity of oxygen forms “red lead,” a substance much used in painting. Lead is found in many parts of England, especially Cornwall, where many lead mines exist; it is got from the sulphuret called “galena,” which is lead in union with sulphur. What is called “black-lead” is not lead at all, but is an ore of iron, being iron in combination with carbon. Lead is about eleven-and-a-half times heavier than water.