VOL. I.] PHILOSOPHICAL TRANSACTIONS. 125 



two rocks, as it were in a cleft ; or be interspersed in the firm rock, like 

 speckled marble ? Or be found in grains like sand or gravel ; as store of excel- 

 lent tin is said to be found in some parts of Cornwall at the sides and in the 

 channels of running waters ; or whether the ore be of a softer consistence, 

 like earth or lome, as there is lead-ore in Ireland holding store of silver ; and 

 iron ore in the north parts of Scotland and elsewhere ? And what is observable 

 in it as to weight, colour, mixture, &c. 



Whether any part of the metal be found in the mine perfect and complete ? 



Whether the mine affords any parcels of metal that seem to grow like 

 plants, as I have sometimes seen silver growing as it seemed out of stone or 

 spar, almost like blades of grass ; as also large grains of a metal, which appeared 

 to me, and which those that tried some of it, affirmed to be gold, abounding 

 in a stony lump, that seemed to consist chiefly of a peculiar kind of spar. 



The depth of the vein. Its concomitants or coat. — ^What are the principal 

 qualities of these extraneous substances : as that spar is white, but transparent, 

 almost like coarse crystal, heavy, brittle, easily divisible into flakes, &c ? Caulk 

 of a different texture, white, opake, and like a stone, but much more pon- 

 derous. Mundick I have had of a fine golden colour. 



Whether the vein oe inclosed every way in its coats ; or whether it only lie 

 between them ? — Whether the vein be uninterrupted, or in some places 

 broken off; and whether it be abruptly or not ; and whether it be by vales, 

 brooks, gullets, &c. ? — How wide the interruptions are ; what signs whereby to 

 find the vein again ? 



What proportion of metal it affords ? as in our iron mines it is observed, 

 that about three tuns of iron-stone will afford one tun of metal : and I have had 

 lead ore, which an ingenious man, to whom I recommended such trials, affirm- 

 ed to me to afford three parts in four of good lead. 



Whether the ore be pure in its kind from other metals ? and if not, of what 

 metals it participates ; and in what proportion ? as I have known it observed, 

 that lead ore, that is poor in its own metal, affords more silver than other ; 

 and I remember that the ore lately mentioned, being rich in lead, scarce afford- 

 ed us upon the cuppel, an atom of silver. And Matthesius informs us, that a 

 little gold is not unfrequently found in iron-ore. And I have by me some 

 gold that never endured the fire, taken out of a lump of tin ore. 



VI. Reduction of the Ore into Metal, 



What are the mechanic and previous operations, as beating, grinding, wash- 

 ing, &c. that are used to separate the ore from the heterogeneous bodies, and 

 prepare it for the fire ? — Whether mercury be made use of, to extract the 



