410 
Cast Steeh 
iron exhibit after having been converted into steel by ce- 
mentation. These blisters are manifestly occasioned by 
the exudation of a gas from the bar, and this gas in all 
probability is oxyd of carbon. A further proof of the ex- 
istence both of oxygen and carbon, even in Swedish bar, 
may be deduced from some interesting experiments by 
Mr. Mushet. Having put some pieces of Swedish bar 
iron into an earthen crucible, with a flux composed of 
marble and calcined clay, he observed first, that the earths 
melted together before the iron showed signs of fusion, 
and that while this latter was melting, bubbles of air were 
continually rising from it and passing through the vitrified 
flux : this gas burnt with a lambent blue flame, and pro- 
bably was gasseous oxyd of carbon : the iron sustained 
a notable loss of weight, and had become considerably 
softer than at first. 
Steel probably is entirely free from oxygen. 
The action of vitrescent earthy mixtures comes next 
to be considered. It is certain that cast iron contains a 
very considerable proportion of scoriae diffused through 
its substance, which are partly got rid of by subsequent 
fusion, as they rise to the surface of the metal, being con- 
siderably lighter than it, while such portions as still re- 
main are got rid of, for the most part, by hammering and 
laminating during the conversion of the cast iron into bar. 
A very small proportion of scoriae, however, is not unfre- 
quently left in the iron, as is obvious from the earthy re- 
sidue that some of the varieties of this metal leave behind 
them when dissolved in acids. It is not yet clearly made 
out what is the precise effect of a little earth on the mallea- 
bility of iron. Clouet has endeavoured to show that it 
renders the iron softer and more malleable, but inclined 
to be hot short, and the experiment by which he demon- 
strates it, is the fusing together of iron and glass, by which 
the effects just mentioned are produced upon the metal 
