Cast Steeh 
413 
cooling or be tempered, so that it is no longer in the state 
of steel. By a still further cementation with charcoal it 
would in all probability be converted into plumb *g°- 
Many chemists have supposed that supercarbonized 
steel is the same thing as crude iron, because they resem- 
ble each other in their fracture and colour and contain 
carbon ; and upon this reasoning have been founded se- 
veral imperfect and ineffectual methods of applying the 
finer kinds of cast iron to some of the uses of common 
cast steel ; but we have shewn that however great may be 
the resemblance in some points, yet cast iron essentially 
differs from steel in containing both earth and oxyd of 
iron, and therefore cannot be substituted for it with any 
success. 
It only remains to say a few words concerning two 
states of bar iron called hot- short and cold-short . 
Iron that is hot- short or red-short is very soft and duc- 
tile when cold, on which account it is generally employed 
in the manufacture of wire ; it may also be hammered and 
welded if treated skilfully at a full white heat, but when 
it has cooled down to a cherry red, it breaks away before 
the hammer and is dissipated almost like sand. 
Cold-short iron on the contrary is harder not only than 
hot-short but also than pure Swedish bar iron ; it may 
be wrought in the usual way when red or white hot, but 
possesses no toughness when cold ; so that a large bar 
may with ease be broken across by a common hand ham- 
mer. 
Hot-short iron is imagined, rather than proved, to con- 
tain arsenic, to which its brittleness at a red heat is sup- 
posed to be owing. 
Cold-short iron is supposed by Bergman to derive its 
characteristic qualities from a portion of phosphoric acid ; 
§uid it is certain that phosphat of iron has been found in 
3 G 
