/ 
128 On the Produétion of Ca/? Tron, 
coloured it, will be left in a difengaged ftate in the furnacés 
When the metal has rifen nearly to a level with the dam, it 
is then let out by cutting away the hardetted loam of the 
fauld, and conveyed by a channel, made in fand, to its pro- 
per deftination ; the principal channel, or runner, is called 
the ow, the lateral moulds are called the pigs. 
In fix days after the commencement of blowing, the fur- 
nace ought to have wrought berfelf clear, and have acquired 
capacity fufficient to contain from 5000 to 7000 weight of 
iron. The quality ought alfo to be richly carbonated, fo as 
to be of value and eftimation in the pig-market. At this 
period, with a quality of coal as formerly mentioned, the 
charge will have increafed to the following proportions :— 
§ bafkets cokes, goolb.; 6 boxes iron-flone, 336]b.; 1 box. 
-limeftone, roolb. 
An analyfis of the {melting operation, and the tendency 
which the individual agents have to produce change in the 
quality and quantity of the iron, come next under confidera-~ 
tion. Let us, however, firft notice the characteriftic features 
exhibited by the different kinds of iron while in fufien, 
whereby the quality of the metal may be juftly defined. 
When fine (No. 1.) or fupercarbonated crude iron is run 
from the furnace, the ftream of metal, as it iffucs from the 
fauld, throws off an infinite number of. brilliant fparkles of 
carbon. ‘The furface is covered with a fluid pellicle of car 
buret of iron, which, as it flows, rears itfelf up in the moft 
delicate folds: at firft the fluid metal appears like a denfe, 
ponderous ftream, but, as the collateral moulds become 
filled, it exhibits a general rapid motion from the furface of 
the pigs to the centre of many points; millions of the fineft 
undulations move upon each mould, difplaying the greateft 
nicety and rapidity of movement,. conjoined with an uncom~ 
monly beautiful variegation of colour, which language is in 
adequate jufily to defcribe. Such metal, in quantity, will 
remain fluid for twenty minutes after it is run from the fur~ 
nace, and when cold will have its furface covered with the 
beautiful carburet of iron, already mentioned, of an uncom- 
monly rich and brilliant appearance. When the furface of 
the metal is not carbureted, it is {mooth like forged iron, and — 
always 
