68 Professor Hausmann on Metallurgical Plienomena 



explanations of the formation of the products of that process ow 

 a comparison of these pioducts that are obvious to view, with 

 those of metal lurgic processes. 



Among those parts of the earth's crust, on which the subter- 

 raneous fiery process has exerted an influence, we recognise part- 

 ly such productions as are indebted to that process entirely for 

 their origin ; partly, masses that have been generated by other 

 causes, and which, either by the communication of heat or by 

 the immediate operation of the productions of the fire, have un- 

 dergone more or less considerable change. The state which im- 

 mediately preceded that in which we at present perceive those 

 productions of the fiery process, might be either that of a vapour, 

 a liquid, or a paste. The masses that are now-a-days ejected 

 from volcanic eruptions are found in all these various states; 

 and we are assuredly justified in assuming that other masses 

 whose fiery origin indeed is not to be questioned, but the nature 

 of whose formation still remains hid, existed in one or the other of 

 those conditions before they passed into a state of solidity : but 

 here it is still not to be forgotten, that the state in which these 

 masses attained their present condition was often perfectly dif- 

 ferent from that in which they originally existed. It would be 

 of importance to geological investigations, if fixed signs could be 

 discovered, by which we might recognise the earlier state ; and 

 perhaps it is possible, from a comparative examination of the 

 productions of the foundry, to make progress in such a discovery. 



First of all, with regard to the transition of bodies from the 

 gaseous state into the solid, a difference takes place in this, — that 

 either the gas passes immediately into the solid state by conden- 

 sation, or not until after it had assumed the liquid state : and by 

 the same kind of evaporation, according, for instance, to the rate 

 of cooling, may the one or the other transition take place. In- 

 stances of this are afforded by certain processes that are em- 

 ployed in procuring zinc and sulphur. Sometimes it is difficult 

 to decide, whethei the one or the other mode of transition en- 

 sued : for similar kinds of aggregation, particularly crystals, may 

 arise in both ways. But we recognise with certainty the earlier 

 molten state in which stalactitical forms, or other distinct indica- 

 tions of previous fluidity, appear. On the immediate transition 

 of the vapours into the solid state, there often arises, especially 



