, Observations on Iron and Steel. 119 
The cast steel is the most valuable, as its texture 
is the most compact and it admits of the finest po- 
lish. 
Sir T. Frankland has communicated a process, 
in the Transactions of the Royal Society,* for weld- 
ing cast steel and malleable iron together; which, 
he says, is done, by giving the iron a malleable, and 
the steel a white heat; but, from the experiments 
which have been made at my request, it appears, 
that it is only soft cast steel, little better than com- 
mon steel, that will weld to iron: pure steel will 
not; for, at the heat described by Sir T. the best 
cast steel either melts or will not bear the hammer. 
It may here be observed, as was mentioned be- 
fore, that steel is an intermediate state between crude 
and malleable iron, except in the circumstance of 
its reduction being complete; for, according to the 
experiments of Reaumur and Bergman, steel con- 
tains more hydrogen gas than cast iron, but less than 
malleable iron ;—less plumbago than the first, but 
more than the latter;—an equal portion of manganese 
with each;—less siliceous earth than either —more 
iron than the first, but less than the second. Its 
fusibility is likewise intermediate, between the bar 
iron and the crude. When steel has been gradual- 
ly cooled from a state of ignition, it is malleable and ° 
soft, like bar iron; but when ignited and plunged into 
* Phil, Trans, 1795. 
