XIX. On Crystals found in Slags. 



By W. H. miller, MA. 



FELLOW OP ST. JOHN's COLLEGE, 

 AND OP THE CAMBRIDGE PHILOSOPHICAL SOCIETy. 



[Read March 22, 1830.] 



The crystals described in the following paper occur in 

 slags found at the bottom of the furnaces in the iron works 

 at Merthyr Tydvil, and at Birmingham. Their primary form 

 is a right rhombic prism, of which Figs. 1 and 2 represent the 

 usual modifications. The angles, which were measured by the 

 reflective goniometer, approximate closely to those of olivine 

 or peridot; their agreement in particular with the angles of 

 peridot, according to Mitscherlich, wuo also used the reflective 

 goniometer in measuring them, is almost perfect. 



The numbers in the first column indicate the law of deriva- 

 tion of the planes, according to the method propo.sed by Professor 

 Whewell, in the Philosophical Transactions for 1825. 



3h2 



