226 
Iron . 
tinually cooled by the application of the same means.™ 
When the decarbonization is compleated, the metal is let 
out at an opening in the side, which has been kept close 
during the operation by a stopping of sand* It flows in- 
to a groove about 18 inches wide, and six or seven feet 
long, constructed of stone in the floor that surrounds the 
furnace. The bottom of the vessel is so placed as to be 
nearly on a level with the floor ; the' only elevation given 
to it being what is merely sufficient' to let the iron run out 
with facility. A considerable quantity of vitreous oxyd 
is formed during the process ; and the loss in the weight 
of metal, which is stated to amount to from £th to 4th, is 
principally referable to this circumstance. The total 
quantity of carbon which the iron contains originally, m 
not estimated at more than drth ; and yet the approach of 
it to the pure state, or, in technical language, to the state 
of bar or wrought iron y after this operation, is very incon- 
siderable* 
The cake of metal procured by these means is broken 
into lumps of a convenient size, and subjected, in a fur- 
nace of another description, to a process known in the 
art by the name of puddling. The furnace, which is also >' 
distinguished by the same term, is a variety of the rever- 
beratory ; and at the immediate point where the flame 
strikes upon the hearth, a shallow concavity is worked i 
out, in which the melted iron is exposed. Opposite to it 
Is a door, and through this the metal is kept in continual 
agitation, by means of a sort of rake, for the purpose of 
exhibiting fresh surfaces perpetually to the influence of 
the air. Water is likewise occasionally thrown in, which 
in some degree contributes to the decarbonization. With 
the loss of carbon, the iron also loses its fusibility, and 
about the middle stage of the operation appears in the 
form of small detached lumps, which scarcely seem ta 
exert any affinity for each other. At length, however, by 
