for Manufa&uring Cajl Iron. 2J 



only 49 grains ; this, when expofed to fire in contact with 

 air, burnt without a refidue ; hence I conclude it to be pure 

 carbon. This iron-ftone in the affay-furnace yields 36 pounds 

 of iron in 100. 



All thefe ftrata of iron-ftone bear the moft evident marks 

 of the agency of water. It is not fo difficult to conceive 

 how regular ftrata of iron-ftone mould be formed by the de- 

 pofition of water : but how fuch huge maffes, broken off, 

 detached, rounded and impreffed with various external fhapes, 

 abounding with the forms of fubftances formerly foreign, 

 now tranfpofed, and forming part of the fame mafs ; regu- 

 larly depofited in ftrata, fometimes incumbent, fometimes 

 decumbent to lime, coal, and their own fpecies, is a work 

 of real admiration ; in attempting to folve which, conjecture 

 muft fupply the place of certainty, and analogy muft ferve 

 in place of ftrict demonftration. 



The manner and difpofition of the Rottenburn ball iron- 

 11 one refembles more an irregular diffufion of wood, felled 

 into lengths, and afterwards changed to ftone ; than a re- 

 gular ftratification, depofited by the decompofition of wa- 

 ter, or the efcape of an acid. 



The phenomena attending water depofiting matter in folu*- 

 tion, and of transforming the nature of vegetables, wood, &c. 

 I have frequently and fatisfactorily obferved. Within the lad 

 four months I have obtained ftrata of an inch thick, whofe fur- 

 face, expofed to the action of the water, difplayed an entire 

 covering of calcareous cryftals of an ice colour, fo fmall as 

 not to be diftinguiflied by the naked eye. The fracture of 

 fuch a thicknefs prefents from 12 to 15 various-coloured 

 ftrata fucceffively depofited; chiefly lime, with a fmall por- 

 tion of fine filcx and magnefian earth. By expofing it a fe\ijt 

 days to drynefs, it acquires confiftency and firmnefs almofl; 

 equal to limcftone. Heat is requifite to difengagc this fe- 

 diment. Its affinity in this cafe is grcateft to wood, lefs to 

 iron, and leaft of all to lead. Pieces of wood boiled in this 

 water become foftcned : the liquid penetrates to the heart of 



the 



