QUESTIONS TOUCHING MINERALS. 407 



imperfect metals may be calcined by continuance of simple 

 fire ; iron thus calcined is called crocus martis. 



And this is their best way. Gold and silver are best cal- 

 cined by mercury. Their colour is grey. Lead calcined is 

 very red. Copper dusky red. 



4. Metals are sublimed by joining them with mercury or 

 salts. As silver with mercury, gold with sal armoniac, mer- 

 cury with vitriol. 



5. Precipitation is, when any metal being dissolved into a 

 strong water, is beaten down into a powder by salt water. 

 The chiefest in this kind is oil of tartar. 



6. Amalgamation is the joining or mixing of mercury with 

 any other of the metals. The manner is this in gold, the 

 rest are answerable : take six parts of mercury, make them 

 hot in a crucible, and pour them to one part of gold made 

 red-hot in another crucible, stir these well together that they 

 may incorporate ; which done, cast the mass into cold water 

 and wash it. This is called the araalgama of gold. 



7. For vitrification. All the imperfect metals may be 

 turned by strong fire into glass, except mercury ; iron into 

 green ; lead into yellow ; brass into blue ; tin into pale 

 yellow. For gold and silver, I have not known them vit- 

 rified, except joined with antimony. These glassy bodies 

 may be reduced into the form of mineral bodies. 



8. Dissolution. All metals without exception may be dis- 

 solved. 



(1.) Iron may be dissolved by any tart, salt, or vitriolated 

 water ; yea, by common water, if it be first calcined with 

 sulphur. It dissolves in aqua forti^ with great ebullition and 

 heat, into a red liquor, so red as blood. 



(2.) Lead is fittest dissolved in vinegar, into a pale yellow, 

 making the vinegar very sweet. 



(3.) Tin is best dissolved with, distilled salt water. It 

 retains the colour of the menstruum. 



(4.) Copper dissolves as iron doth, in the same liquor, into 

 a blue. 



