Tut. True. There are various kinds of it: white, black, yellow, gray, mottled and veined with different colours; but all of them are hard and heavy stones, admitting a fine polish, on which account they are much used in ornamental works.
Geo. I think statues are made of it?
Tut. Yes; and where it is plentiful, columns, and porticoes, and sometimes whole buildings. Marble is the luxury of architecture.
Har. Where does marble come from?
Tut. From a great many countries. Great Britain produces some, but mostly of inferior kinds. What we use chiefly comes from Italy. The Greek islands yield some fine sorts. That of Paros is of ancient fame for whiteness and purity, and the finest antique statues have been made of Parian marble.
Har. I suppose black marble will not burn into white lime?
Tut. Yes, it will. A violent heat will expel most of the colouring matter of marbles, and make them white. Chalk is another kind of calcareous earth. This is of a much softer consistence than marble; being easily cut with a knife, and marking things on which it is rubbed. It is found in great beds in the earth; and in some parts of England whole hills are composed of it.
Geo. Are chalk and whiting the same?
Tut. Whiting is made of the finer and purer particles of chalk washed out from the rest, and then dried in lumps. This you know is quite soft and crumbly. There are, besides, a great variety of stones in the earth harder than chalk, but softer than marble, which will burn to lime, and are therefore called lime-stones. These differ much in colour and other properties, and accordingly furnish lime of different qualities. Whole ridges of mountains in various parts are composed of lime-stone, and it is found plentifully in most of the hilly counties of England, to the great advantage of the inhabitants.
Geo. Will not oyster-shells burn into lime? I think I have heard of oyster-shell lime.