250 



easily divided by water, though not by fire. It ever 

 comes purer out of the fire. Yet it will fuse in a very 

 intense heat. 



Ail salt dissolves by moisture : but moisture only 

 dissolves a certain quantity. Yet when it is impreg- 

 nated with any salt, as much as it can bear, it will still 

 dissolve a considerable quantity of another kind of 

 salt. It seems, the particles of this, being of different 

 figures, insinuate into the remaining vacuties. Thus 

 when a cup of water will dissolve no more common 

 salt, alum will dissolve in it. And when it will dis. 

 solve no more alum, salt-petre will dissolve, and after 

 that, sal ammoniac. 



The most remarkable salt-mines in the world, are 

 in the village Willisca, five leagues from Cracow in 

 Poland. They were first discovered above 500 years 

 ago ? in the year 1251. Their depth and capacity are 

 surprising. They contain a kind of subterranean re. 

 public, which has its laws, polity, carnages, and pub- 

 lic roads for the horses which are kept there, to draw r 

 the salt to the mouth of the quarry. These horses 

 after once they are down, never see the light of the 

 day again. But the men take frequent occasions of 

 breathing the upper air. When a stranger comes to 

 the bottom of this abyss, where so many people are 

 interred alive, and where so many were born, and have 

 never stirred out, he is surprised with a long series of 

 lofty vaults, sustained by huge pillars, which being all 

 rock salt, appear by the light of flambeaus that are 

 continually burning, as so many crystals, or precious 

 stones of various colours. 



11. To this class, secondly, belong stones, which 

 are hard, rigid, void of taste, reducible to dust by the 

 hammer, and into a calx by fire. It is probable that 

 stones, like salts and most fossils, are generated from 

 a fluid, which gradually hardens into stone, by the 

 evaporation of its finer parts. 



