Gravity
See SPECIFIC GRAVITY.
Gray Pig-iron is all pig-iron that contains a large proportion of its carbon in a graphitic state. Such irons may be distinguished by their crystalline fracture and dark-gray color. See CAST IRON.
Green-sand is moulding-sand in a moist condition, and suitably mixed to form moulds in which the metal can be poured at once, without subsequent drying. See FACING-SAND; DRY-SAND MOULDING; GREEN-SAND MOULDING; DAMPNESS.