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VII. On the Combinafiojis of Carbon with Silicon and Iron 

 and other metals, forming the different species of Cast Iron, 

 Steel, and Malleable Iron. By Dr. C. Schafhaeutl, of 



Munich . 



[Continued from vol. xv. p. 428.] 



THE 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 v^^ill 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- 

 ploy 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 



