406 
Cast Steel. 
of the carbon itself in the hydrogen : for, says he, the gas 
when burnt with oxygen procured from manganese, in- 
flamed like common hydrogen, and whether procured by 
means of iron, or steel, or wootz, produced only a very 
slight turbidness with lime-water ; whereas carburetted 
hydrogen, prepared by passing steam through hot char- 
coal, being treated in the same manner, rendered the lime- 
water quite milky. The proportions of gas from iron 
and steel were also remarkably less than those mentioned 
by Berthollet. 100 grains of wootz, by several experi- 
ments, yielded from 78 to 84 ounce measures of gas. 
100 grains of steel wire, also by various experiments, 
yielded from 83 to 86 ounce measures of gas. 100 
grains of iron wire yielded from 86 to 88 ounce mea- 
sures. 
How much soever the experiments of Berthollet and 
Dr. Pearson differ in other respects, yet we may infer that 
Swedish bar iron contains a larger proportion of reguline 
iron than the other varieties of bar iron, that steel contains 
a smaller proportion than bar iron, that wootz contains a 
still smaller proportion, that grey cast iron is inferior in 
this respect to steel, and that white cast iron is the least 
pure of any. 
We also learn that the lower the temperature is at 
which the solution of the iron is made, the purer is the 
h} drogen that is produced, and with proper care that the 
objections raised by Berthollet to the accuracy of this 
mode of proceeding, may be completely done away . (?T. C.) 
W e have already mentioned that almost all the known 
varieties of iron and steel contain a larger or smaller pro- 
portion of carbon. The quantity of this in any particu- 
lar sample of metal may best be ascertained by digesting 
the metal in dilute nitro- muriatic acid, which will leave 
untouched the carbon united with a little iron. This 
black insoluble residue being washed in warm water and 
