THE ROYAL ARTILLERY INSTITUTION. 
305 
The charge of crude iron is melted with coke in an ordinary cupola, and 
the contents are tapped out into a crane ladle. This is swung round by the 
crane and the contents emptied* into the open hopper of the converter. 
The molten iron falls on the cast-iron plate, and re-action is soon evidenced 
by the appearance of white and grey vapours out of the converter funnel. 
The plate is melted up with the charge; a burst of brilliant yellow flame 
indicates when the re-action is at its height. This lasts for from three to five 
minutes, with 15 cwt. charges, and then rapidly subsides. 
The conversion is now complete. The converting pot is detached and 
rolled away, and the converter is ready for another bottom and another 
charge. 
In the converter is the converted metal called crude steel, covered with a 
slag at IT J inch thick, consisting of the soda of the nitrate, combined with 
silica and clayey matter, a small quantity of metallic iron and silicate of 
iron. The liquid mass beneath is not sufficiently fluid to be tapped, so the 
converting pot is upset on the iron floor, and is broken into lumps of a 
convenient size to be brought, after a little renewal of heat, under the 
shingling hammers and patted into cakes of “ crude steel.” 
This is metal of the purest and finest quality, from which, by two different 
methods of treatment, either very strong, but soft, tough, and malleable 
wrought-iron may be made, or fine cast steel. 
The above is the whole process of conversion. 
The following are certified as the average rupturing strains and extensions 
at rupture of the steel iron and cast steel, resulting from a series of 
experiments:— 
Heaton’s steel iron 
n cast steel 
Rupturing strain 
in tons 
per square inch. 
22-72 
41-73 
Extension at 
rupture in per cent 
of original length. 
21-05 
7-20 
These specimens have been manufactured from “ makes ” of crude iron, 
obtained from various and distant iron districts in Great Britain. 
