3i 6 Elements of Mineralogy. 



4 per cent, of calx of zinc; a good orefhould 

 afford at leaft 30 per cent, and its fpecific 

 gravity be about 4,400 or 5,000. 



8. Sometimes calamines contain a mixture 

 of calcareous earth and lead. 3 Lin. <von 

 Gmel. 112. Moft of the Engliih calamines 

 contain lead. 



9. The firft and fecond Varieties are eafily 

 analyfed in the moift way, by diflblving them 

 in the dilute vitriolic acid ; the filex, if any, 

 will remain undiffblved, and the zinc and 

 iron are taken up, and may be feparated by 

 adding a 1 piece of zinc previoufly weighed, 

 and boiling the folution; the iron will be 

 precipitated 5 the folution, which then con- 

 tains only zinc, fhould be precipitated by 

 aerated mineral alkali. 193 gr. of this pre- 

 cipitate are equivalent to 100 of zinc in its 

 metallic form, from which the weight loft 

 by the inferted zinc fhould be fubtraded ; the 

 weight of the fixed air and water may be 

 colle&ed by comparing the lofs of weight 

 which the ore fuffers by calcination and folu- 

 tion in acids. 



10. The analyfis of the 3d Variety, or ca- 

 lamine, is more complex. Mr. Bergman 

 gives us two methods of performing it. The 

 firft is to dephlogifticate it in the nitrous acid 



with 



