294 OBSERVATIONS UPON THE GABMIA 



and to those which might be drawn from the circum- 

 stance of its being found in the vicinity of a furnace, 

 I have been able to obtain the evidence of men to the 

 fact of its having been formed in it. Having been 

 informed that ore from the same bed was used at 

 the works belonging to Messrs. Eolley and C offing, 

 near Salisbury, I repaired there with a hope of find- 

 ing the cadmia near that furnace also. After a short 

 search, I found it in its immediate vicinity, and was 

 informed by Mr. Holley, that he had himself taken 

 it out of his furnace about twelve years ago, when 

 they renewed the stack. He was positive that it was 

 the same ; that it had been found about six feet below 

 the orifice of the furnace, and that if not occasionally 

 removed, it would have eventually choked it. I even 

 understood him or his partner to say, that this sub- 

 stance was even at present occasionally formed in 

 the furnace in pieces of almost one-eighth of an inch 

 in thickness. One of the reasons why it is still form- 

 ed at Salisbury, and not at Ancram, is probably 

 owing to the ore used at Ancram being picked, and 

 the other not. Mr. Patterson thinks his ore is also 

 better roasted. 



According to Mr. Heron de Villefosse, a similar 

 substance is formed in the copper and lead furnaces 

 of Julius, Sophia, and Ocker, near Goslar, in the 

 Hartz. At Goslar, as well as at Jemmapes in Bel- 

 gium, this cadmia is considered as the best material 

 that could be used in the manufacture of brass ; as it is 

 purer than the roasted calamine, it is preferred to it, 

 as well as to all other zinciferous substances. It had 



