356 Elements of Mineralogy. , v 



with half its weight of borax in a crucible 

 lined to the thicknefs of ~ of an inch with 

 a mixture of charcoal and a little clay, and 

 expofing it to the fire of a fmith's forge for 

 three quarters of an hour. 



8. The regulus is of a fteel grey colour, 

 fiot fo hard as cobalt, exceeding brittle, not 

 magnetic in fmall pieces, though flightly fo 

 when powdered. Its texture is granular ; 

 its fpecific gravity about 6,710. 



9. Its fufibility is nearly as that of cop- 

 per, and it feems to contain fomething more 

 phlogifton than iron does ; it is not volatil 

 when heated. 



10. It is very difficultly foluble in any 

 acid, and requires the affiftance of heat ; arter 

 ebullition for fome days ihe nitrous acid out 

 of 5 grains diffolved only 4, aqua regia 4,2, 

 dilute vitriolic acid 3,5, and the marine 3. 

 Infufion of galls turns thefe folutions black ; 

 the Prujfian alkali gives a dark blue precipi- 

 tate, and common alkalis a white precipitate, 



11. It precipitates gold, filver and copper 

 very flowly from their folutions, and in their 

 metallic form ; but lead from nitrous acid in 

 the form o a calx; it does not precipitate 

 rriercury from the nitrous agidi 



