Part 37 (1/2)

What is Slate?

The co out of the quarry, and easily cut or split into thin plates,--a property which renders it invaluable for a variety of purposes

_Invaluable_, extremely valuable

For what is it used?

Slate has superseded the use of lead for covering roofs, even of the largest buildings; being lighter and more durable, it is preferable to tile: it is also employed for slabs to form cisterns, shelves for dairies, and other purposes, on account of its strength, coolness, and the ease hich it can be cleaned; the latter quality renders it also of great value in the business of education, as a cheap substitute for paper The ancients were unacquainted with the use of slate

What other kinds of stone are used in building?

Liist: of these there are many varieties Those which are easily cut and polished are termed marbles, and are used in sculpture and in ornamental architecture The coarser

_Calcareous_, partaking of the nature of calx or lime,--a term employed to describe chalk, marble, and all other coist_, one who studies the science of Geology

Of what do Calcareous Earths or Stones consist?

Calcareous earths, stones, or rocks consist of lime, or pure calcareous earth, carbonic acid, and water

What is Quick-Lime?

Li subjected to an intense heat in a kiln

How are these Stones wrought?

To whatever purpose the stones are to be applied, the larger blocks obtained froeable pieces by sawing: the saw used is a long blade of steel, without teeth, fixed in a heavy wooden frae saws are worked by one or two men who sit in boxes to shelter them from the weather; water is caused to drip constantly into the cut, to facilitate the motion of the saw, and keep it cool, so as to prevent it froe

_Tenifies the state to which they are reduced, especially with regard to their hardness

What is Steel?

Iron combined with a small portion of carbon; its chemical name is _Carburet of Iron_ It is not so malleable as iron in its ordinary state; but is her polish Of this material areinstrue tools, used for domestic purposes and in the arts, from the ponderous pit-saw to the finest lancet Good steel is much more ductile than iron; and a finer wire may be drawn froe-tools depends upon their teist is one who studies Geology: what is meant by this term?