1blow into the furnace in either a mild or a
vigorous manner.
For those ores
which heat and fuse easily, a low hearth is necessary for the work of the
smelters, and the pipe must be placed at a gentle angle to produce a mild
blast from the bellows. On the contrary, those ores that heat and fuse
slowly must have a high hearth, and the pipe must be placed at a steep incline
in order to blow a strong blast of the bellows, and it is necessary, for this
kind of ore, to have a very hot furnace in which slags, or cakes melted from
pyrites, or stones which melt easily in the fire15, are first melted, so that the
ore should not settle in the hearth of the furnace and obstruct and choke up
the tap-hole, as the minute metallic particles that have been washed from
the ores are wont to do. Large bellows have wide nozzles, for if they were
narrow the copious and strong blast would be too much compressed and too
acutely blown into the furnace, and then the melted material would be
chilled, and would form sows around the nozzle, and thus obstruct the opening
into the furnace, which would cause great damage to the proprietors'
property. If the ores agglomerate and do not fuse, the smelter, mounting
on the ladder placed against the side of the furnace, divides the charge with
a pointed or hooked bar, which he also pushes down into the pipe in
which heat and fuse easily, a low hearth is necessary for the work of the
smelters, and the pipe must be placed at a gentle angle to produce a mild
blast from the bellows. On the contrary, those ores that heat and fuse
slowly must have a high hearth, and the pipe must be placed at a steep incline
in order to blow a strong blast of the bellows, and it is necessary, for this
kind of ore, to have a very hot furnace in which slags, or cakes melted from
pyrites, or stones which melt easily in the fire15, are first melted, so that the
ore should not settle in the hearth of the furnace and obstruct and choke up
the tap-hole, as the minute metallic particles that have been washed from
the ores are wont to do. Large bellows have wide nozzles, for if they were
narrow the copious and strong blast would be too much compressed and too
acutely blown into the furnace, and then the melted material would be
chilled, and would form sows around the nozzle, and thus obstruct the opening
into the furnace, which would cause great damage to the proprietors'
property. If the ores agglomerate and do not fuse, the smelter, mounting
on the ladder placed against the side of the furnace, divides the charge with
a pointed or hooked bar, which he also pushes down into the pipe in
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