292 OBSERVATIONS UPON THE C ADM I A 



from the decomposition of oxidule or oligist iron ore. 

 We know that this shist contains blende or sulphuret 

 of zinc, in some places at least, as at the Ancram lead 

 works, and this may account for the presence of zinc. 



Mr. Eouesnel has endeavoured to explain the 

 formation of these cadmia, in a manner which does 

 not appear to me to be satisfactory ; 1 would rather 

 admit that it results from a reduction of the oxide or 

 carbonate of zinc, which is intermixed in small quan- 

 tities with the iron ore; that this reduction takes place 

 in the furnace ; that the zinc sublimes and oxydates 

 as it rises, and settles in the form of a ring at the in- 

 ferior part of the charge, where the temperature of 

 the furnace is considerably lowered by the successive 

 additions of cold ore, charcoal, &c. 



This substance is not, it is true, found at present 

 forming in the Ancram furnace ; but this may in a 

 great measure be owing to a better roasting of the ore, 

 previous to its introduction into the furnace. It may 

 also be occasioned by the circumstance that all the 

 ore destined for Ancram is picked with great care, 

 at the ore bed. 1 must not, however, omit to state 

 that I found in the flue erected above the orifice of 

 the furnace, for the protection of the workmen, a red 

 pulverulent substance, to which the workmen have 

 given the name of sulphur, a name which, as the 

 editor of the Emporium has well observed, has been 

 most unfortunately given by furnace and forge men, 

 to every product which puzzles them, and without 

 any regard to its real composition : this powder I 

 supposed to be a mixture of ashes and fine ore, blown 



