72 Professor Hausmanu on Metallurgical Phenomena 



and partly with an oxidized surface, forms the basis on which 

 the graphite is deposited. Here we perceive manifestly that the 

 graphite vapour was condensed after the liquid iron had been 

 deposited in that form, on the smooth surface of the rigid slag. 

 There is a circumstance worthy of note attending it, — iron and 

 graphite are found always together, and only on the upper part 

 of the hardened slag : hence we must conclude, that the iron too 

 gained access to the slags in the form of vapour, but became 

 liquid before it passed into a solid state ; whereas, graphite was 

 immediately crystallized. If this opinion be correct, it follows 

 necessarily that iron requires a higher temperature for its subli- 

 mation than carbon. 



In the case of the phenomena described here, a comparison 

 with the filling up of cavities in amygdaloids is forced upon us. 

 Here too, sometimes the whole space, sometimes only part of it, 

 appears filled, and often only the covering sprinkled. In these 

 cases too, a certain succession is observed in the deposition of the 

 different mineral bodies which coat or fill the cavities ; here also 

 we perceive bodies which were liquid before their transition into 

 the solid state, and afterwards assumed either botryoidal and 

 stalactitic, or crystalline forms : while, on the contrary, other 

 bodies appear to have passed at once from a state of vapour into 

 the crystalline condition. No contradiction is felt between this 

 kind of completion of the cavities in many amygdaloids and that 

 which takes place by filtration, and which in other cases displays 

 itself unequivocally. The formation of a large proportion of the 

 veins, particularly of those containing ore, bears a strong analogy 

 to the filling of the cavities in amygdaloids ; and, indeed, there 

 not unfrequently takes place a real transition between imbedded 

 globular and amygdaloidal masses, and the materials forming 

 veins. The manner of alternation among various vein stones paral- 

 lel to the chief bounding surfaces ; — the certain regularity of that 

 alternation, which appears, as well in the filling up, as in single ca- 

 vities; the mode in which one mineral form s a layer over another ; 

 —the growth on those parts of crystals inclined downwards ; and 

 many other phenomena, are only to be satisfactorily explained, on 

 the supposition that the mineral substances gained access to the 

 veins in a state of vapour. The various forms which vein stones 

 have assumed, may also be explained from the results of the con- 



