Shackle
A link with an open end, the extremities of which are forged to receive a pin or bolt, by which means a connection may be made with a chain; or it may be employed to join two chains together. Some are made link-form, and others are made like a ring. Their chief use in the foundry is to handle heavy cores and flasks, for which reason the eyes should be always made large in order that strong pins or bolts may be inserted. If pins are used, one end should be jumped and the other keyed, to prevent slipping out. The nut answers this purpose when a bolt is used.
Shakdo is a Japanese bronze of great beauty, the composition of which consists of copper containing from one to ten per cent of gold. Its bluish-black color is preserved by boiling the polished article in an artificial bronze solution composed of sulphate of copper, alum, and verdigris. See BRONZE. Shale is a hard, slaty clay composed chiefly of silica and alumina, but in some instances containing lime and oxide of iron. It forms in the coal-measures and often contains a quantity of bitumen: it is then known as bituminous shale, from which variety shale-oil is obtained by distillation. Shale has a slaty structure, generally grayish black in color, but red when iron is present. Slate-pencils are made from it, and when free from iron and lime it is ground up and used for making fire-bricks. See BITUMEN.