Iron. 289 



a yellow colour ; co&ion may be requifite at 

 the end. 



45. Many ores, which are difficultly fo- 

 luble before calcination, become eafily foluble 

 after they are calcined. 



46. To difcover fiderite in an ore, it fhould 

 be diflblved in dilute vitriolic acid 3 the folu- 

 tion, after ftanding fome hours, will depofit 

 a white calx, if fiderite be contained in it. 



In the dry Way. 



47. Mr. Morveau recommends the follow- 

 ing flux for all iron ores: 8 parts pulverifed 

 glafs, i of calcined borax, and { of charcoal, 

 well mixed j of this flux he takes two parts, 

 or, if the ore be very poor, 3 parts, and i of 

 the ore, and places them in a crucible, lined 

 with a mixture of a little clay, and pounded 

 charcoal |- of an inch thick, to which a cover 

 is luted : this he places in a fmith's forge, 

 and urges it with a ftrong heat for half an 

 hour ; to find whether the ore requires calci- 

 nation, he inftitutes this trial with equal 

 weights of the ore calcined and uncalcined, 

 and compares the refults ; the weight of the 

 ore fhould not exeed 60 grains. 



48. Mr. Bergman efiay s the white fparry iron 

 ore by placing it in a crucible lined with char- 



U coal 



