Cast Steel. 
40S 
in diameter and one inch in thickness. When cold it is 
uncommonly refractory, neither breaking nor bending un- 
der the hammer. It is not nearly so easy to be filed as 
either bar or cast steel before these have been hardened : 
it takes an extremely high brilliant polish ; its fracture is 
moderately close, resembling that of blister- steel that has 
been heated and hammered a little. When nearly white 
hot it is malleable, but is much more likely to crack un- 
der this treatment than even cast steel ; it requires there- 
fore much care, labour, and time to fashion it into any re- 
quired shape. When made white hot, it exhibits the glas- 
sy smooth surface of welding iron, but when struck very 
gently with a hammer, it cracks in many places, and by 
a harder blow is shivered to pieces. When brought to a 
high heat and quenched suddenly in cold water, it be- 
comes harder than at first, thoughmot equally so with the 
finest cast steel in similar circumstances ; but on the other 
hand, it is not capable of being sensibly softened by an- 
nealing as the other varieties of steel are. At a high heat 
it is fusible, and after being melted exhibits a close com- 
pact grain, is considerably brittle, and bears a very near 
resemblance to cast steel. From its analysis and other 
circumstances, it is considered by Dr. Pearson as differ- 
ing from steel, only in containing a little oxyd of iron. 
Comparison and analysis , of Cast Iron , Bar Iron, and SteeL 
Notwithstanding the close attention of various eminent 
chemists to this important subject, much yet remains to 
be done before an entirely satisfactory theory can be form- 
ed to account for the different properties possessed by the 
various kinds of iron and steel. We shall endeavour to 
show in the present section, the progress that has already 
been made in this interesting analysis, and shall then point 
out some of the chief difficulties that yet remain to be 
overcome. 
