1 * 3:2 
MINUTES OF PEOCEEDINGS OF 
Department. Each cupola is capable of running about ten tons in an hour, 
but the quantity will vary with the rate of driving. There are two rows of 
tuyeres. The upper one is generally not used; if, however, it is desired to 
increase the yield, the upper row may be used. The cupolas are blown out, 
and undergo minor repairs daily. They were formerly lined with fire-brick, but 
now ganister is employed, by which a considerable saving is effected.*' The 
furnaces require re-lining about once a fortnight. 
In August, 1874, a charge for the cupola consisted of:— 
Gun iron ...... 30 
Old shell . 60 
No. 1 Eidsdale or Cwmbran. 10 
100 
About 1^ cwt. of coke is used to 10 cwt. of iron, and | cwt. of chalk is 
added. The use of the chalk is to combine with the silica always present 
in pig-iron (the pigs being cast in sand moulds). If the chalk was not 
added, the silica would combine with the iron and cause a loss. Lime, also, 
gives a fluid slag which disengages readily from the iron, thus preventing its 
entry into the castings. If too much lime is used the lining of the furnace 
is rapidly eaten away; the sand of the lining combining with the lime. A 
thick strong slag sometimes causes scaffoldingthe slag forming a net¬ 
work which, for a time, supports the superincumbent charge, but which finally 
gives way, and the fall of the heavy mass into the molten metal may cause an 
accident. 
The charges of iron above given must be taken as approximate only, 
as they are liable to vary from day to day according to the quality of 
the old shells, guns, and pig-iron employed. The foreman in charge states 
that even the weather has an effect on the nature of the metal produced by 
the furnaces. The object in view is to produce a sound, close iron, not too 
hard to turn. The furnaces are tapped about every ten minutes (when 
ladles containing about 6 cwt. are used), and the slag is run off about every 
three hours. The heat of the furnace depends on the rate of driving, &c. 
It is necessary to have the iron very hot to produce sound castings. 
The metal is run into iron ladles lined with loam, containing about 6 cwt., 
from which smaller ladles containing about \\ cwt. are filled, and thence the 
metal is poured into the moulds; care being taken to pour with sufficient 
rapidity to keep the runners filled, so that any cinders may remain on top, and 
not be carried down into the shell.ff Gas is formed from the coal-dust in 
the moulds and core, and burns out through the perforations of the mould 
and at the neck of the hollow spindle. The shells are allowed to remain 
about an hour in the moulds. Eor large shells—8-in. and upwards—cranes 
are necessary for lifting. A convenient form for casting is to have a ring 
with a revolving crane in the centre. 
Moulds and Cohes. 
The material employed is sand and coal-dust, brought to the desired con¬ 
sistency by mixing “green sand”—-that is, sand which has not been pre- 
* Ganister is the name given to a species of silicious stone, 
f A small strainer made of clay is placed in top of the runner of larger shells. 
