[ 44 ] 
VII. On the Combinations of Carbon *with Silicon and Iron 
and other metals^ fo7ining the different species of Cast Iron, 
Steel, and Malleable Iron, By Dr. C. Schafhaeutl, of 
Munich , 
[Continued from vol. xv. p. 428.] 
T he chemical ingredients of the iron are easily to be ascer- 
tained ; but the information thus obtained is of no value in 
investigating the real chemical nature of iron, and can only 
be used as a preliminary method which must guide or verify 
further proceedings. 
1 will only here remark, that by separating silica in the 
usual way by means of alkalis, there is considerable difficulty 
in rendering silica insoluble in water when combined with a 
great quantity of oxide of iron, it requiring a great length of 
time to drive away the last traces of water and acid from the 
evaporated solution; and by a quick evaporation, if the residuum 
is not heated almost to a red heat, the silica either dissolves 
in a great measure again, or goes through the filter after a 
most tedious filtering process. It is always a laborious pro- 
cess, causing much loss to separate it afterwards, when the 
solution contains manganese. On the contrary, if the heat is 
increased to so high a degree, the separated silica retains a 
great quantity of oxide of iron, from which it is the most 
readily freed by treating it, after ignition, with hot chlorohy- 
dric acid ; I mention this purposely, as Baron Thenard cau- 
tions us to use, for evaporating the solution containing the 
silica, only a moderate heat, in order that the chlorides may 
not be decomposed. 
In ascertaining the exact quantity of carbon, of more than 
half-a-dozen given directions one only is of real value, which 
was likewise first used by Berzelius, viz. the burning the iron in 
a current of oxygen gas, or mixing it with chlorate of potash 
and chromate of lead, and igniting it in a glass tube after the 
well-known practice used in the analysis of organic bodies. 
All other methods give, instead of pure carbon, carbon com- 
bined with silicon, or carbon combined with hydrogen, azote, 
and silicon. 
To ascertain the quantity of azote, where the metal is in 
large quantity, I use Dumas's method, viz. the combustion of 
iron in a vacuum ; but where the quantities are small, I em- 
])loy the following means. I put into a tube of German glass, 
from four to five lines wide, and about twelve inches long, 
shut at one end, a few grains of the body from which I intend 
to separate the azote, and afterwards about six times its weight 
of a mixture of caustic potash and caustic barytes; the open 
