A glossary of mining and metallurgical terms

68 A GLOSSARY OF MINING AND METALLURGICAL TERMS.
Proving-hole. A small heading driven to find and follow a coal-
seam, lost by a dislocation.
Pryan. Ore in small pebbles mixed with clay.
Pudding-stone. A conglomerate in which the pebbles are rounded.
See Breccia.
Puddle-bnrti. See Forge.
Puddle-stee/. See Steel.
Puddle-train. A train oi' rolls for reducing squeezed puddle-balls
to puddle or muck-bars.
Puddling. 1. The process of decarburiziiig- cast iron by fusion on
the hearth of a reverberatory furnace, lined (fixed or fettled) with
ore or other material rich in oxide of iron. The bath is stirred
with a rabble to expose it to the action of the lining and of an air
current. The escape of carbonic oxide causes it to boil, whence the
early name of this method of puddling, viz., boiling. Dry puddling is
performed on a silicious hearth, and the conversion is effected rather
by the flame than by the reaction of solid or fused materials. As the
amount of carbon diminishes the mass becomes less fusible and be-
o'ins to coagulate {come to nature), after which it is worked together
into lumps {puddle balls, loups) and removed from the furnace to be
hammered (shingled) or squeezed in the squeezer, which presses out
the cinder, etc., and compacts the mass at welding heat, preparatory
to rolling. Silicon and phosphorus are also largely removed by pud-
dling, pa.ssing into the cinder. Mechanical puddlers (in which the
bath is agitated by revolution, or by mechanical rabbles, to save hand-
labor) are employed to a limited extent. 2. The term puddling,
now applied in metallurgy exclusively to the above process, origi-
nailv referred to the puddling of clay or clay and charcoal upon
the masonry of a furnace hearth, to form a lining. Ditches, reser-
voirs, etc., SLve puddled with clay to make them water-tight.
ore.
Pug-tub. See Settler.
Pulley-frame. Gallous-frame.
Pulp, Pac. Pulverized ore and water; also applied to dry-crushed
Pulpj-assay, Pac. The assay of samples taken from the pulp
after or during crushing.
Pump-bob. See Bob.
Pump-rod. The rod or system of rods (usually heavy beams) con-
necting the steam-engine at the surface, or at a higher level, with
the pump-piston below. See Balance-bob.
Pump-station. See Station.