THE PRODROMUS 249 



layers, just as rhomboidal selenites are rhomboid bodies which 

 are broken up into other rhomboidal bodies.^ And there are 

 various other bodies which, although differing from the crystal 

 in many respects, still all agree in this, that they were formed 

 in a fluid and from a fluid. This is true also of talc, the most 

 famous among chemical substances; so that they are by no 

 means mistaken who believe that the solid body of talc can be 

 resolved into a fluid body, seeing it is beyond cavil that talc 

 was formed from a fluid. But there is no doubt that they are 

 as far as possible astray from the truth who strive to wrench 

 this token from it by means of fire's violence ; for talc, accus- 

 tomed to kindlier treatment at Nature's hands, scorning so 

 great barbarity in lovers of beauty, by way of revenge yields to 

 the fire-god that function of self-destruction which it keeps 

 closed within itself.^ 



If a careful investigation of angular bodies should be begun, 

 touching not only their composition but also their decomposi- 

 tion, we should soon gain a sure knowledge concerning the 

 diversity of the motion by which the particles of both the atten- 

 uated fluid and the surrounding fluid are driven on ; and this 

 branch of physics is as essential to all for a true understanding 

 of the workings of Nature as few they be that pursue it. 



SHELLS OF MOLLUSKS 



Among solids naturally enclosed in a solid none occurs more 



p. 53. commonly, or occasions greater doubt, than the shells of mol- 



lusks. Concerning these, therefore, I shall speak at somewhat 



1 The reference appears to be to the cleavage of selenite. 



2 Talc was " famous " in alchemy. Compare White, The Hermetic and Alchemical Writ- 

 ings of Paracelsus, Vol. II, London, 1894, p. 383 {A Short Lexicon of Alchemy) : 



" The older alchemists have often made reference to what they term an Oil of Talc, to 

 which they have attributed so many virtues that subsequently chemists have exerted all their 

 power to compose it. They have calcined, purilied, and sublimed the matter in question, but 

 have met with no success. The reason is that the term was used allegorically, and that the 

 reference was to the Oil of the Philosophers, the elixir at the white." 



See also Robert Boyle, The Usefulness of Philosophy (edition of P. Shaw, London, 1725, 



Vol. I, p. 67) : 



" But a credible person, disciple to Cornelius Drebell, cou'd do more than this. He assur'd 

 me, he had a way of building furnaces, wherein he, by the single force of fire, made Venetian 

 talc flow ; which I confess myself unable to do by the fire of a glass-house." " Talc, usually 

 employ'd in cosmetics, is of so very difficult calcination, that eminent chymists have look'd 

 on all calces of talcs as counterfeit." Ibid., p. 158. 



