516 Dr. Schafhaeutl on the Different Species of 



assume that the metallic iron is in combination with carbon, 

 azote and hydrogen, or perhaps in a state forming a sort of 

 cyanet of iron. 



The relation of the quantity of constituents of the brown 

 residuum of the iron is so stable and so accurately in atomic 

 proportions, that we may safely conclude the quantity of carbon 

 from the amount of oxygen absorbed. 



If we denote the increase of weight by letter (a), the oxygen 

 of silicon as (s), the oxygen of iron by (/"), and the carbon 

 by (.a'), we obtain always the following simple formula, par- 

 ticularly when we consider that the iron is oxidized according 



. 3 ... 

 to the above-mentioned formula F F : 



^ = 5 + f — a. 



In some French irons I found the relations of carbui'ets pf 

 iron to the siiiciuret approach 



S C\ 

 F4 C^. 



If we further consider, that the white silica only remains 

 when the iron residuum has been exposed to a number of ig- 

 nitions, and that after only a few ignitions it remains always 

 dark black, soluble neither in alkalis nor acids; we may find 

 therein likewise aproof, that silicon is combined chemically with 

 carbon. Further, the remainder of the residuum five times 

 ignited had gained 0"028 grains, after the black-coloured 

 scales had disappeared ; this increase in weight can only be 

 ascribed to the oxidation of those black scales, which must have 

 been a metal whose oxide was white. Further, if we consider 

 that the remainder of the residuum only once ignited, after 

 having changed its deep-black colour to white, and after emit- 

 ting a great quantity of smoke, had only lost 0'0511 grains; 

 we may take all these circumstances as a certain proof that 

 the silica obtained from these residuums must have been con- 

 tained in the metallic state, and in combination with carbon, 

 which is likewise to be suspected from its emitting bright red 

 sparks when thrown into the flame of a candle. 



Having now considered partially by induction the relative 

 combination of the ingredients of the residuums of white 

 irons, we proceed to ascertain by experiment the quantity 

 of the volatile bodies in the residuums. 



60 grains of the same Maesteg white iron, freed from ail fine 

 powder, and treated in a retort with 4 oz. of hydrochloric acid 

 of sp. gr. I'lOS, generated no spongy foam whatever; the li- 

 quid in the retort always remained transparent, and the action 

 of the acid had ceased the next day. 



13"71 1 grains of this residuum, corresponding with 35 grains 



