Examine CaCO3-marble, limestone, chalk, not crayon,-CaSO4 - gypsum or selenite-CaCl2, CaO.
249. Occurrence.-The above are the chief compounds of Ca. The element itself is not found uncombined, is very difficult to reduce (page 141), is a yellow metal, and has no use. Its most abundant compound is CaCO3. Shells of oysters, clams, snails, etc., ar