9° 



CHEMICAL ANALTSIS 



exhibited nearly the fame chemical properties, the refults only, 

 in each example, flaall be mentioned. 



ANALYSIS ir. 

 Whin of Salijbury Rock. 



The fpeclmen employed was chofen from the fouth fide of 

 the cragg, and was perfedly hard and free from decompofition, 

 as the particular fpot from which I broke it had been quarried 

 a fliort time before. 



A DESCRIPTION of its extcmal charadlers may be found in 

 p. 54. of this volume. Its powder is light greenifh-grey ; but 

 after being Wet, acquires a dirty green colour. When heated 

 to rednefs, it becomes light brown. Though not attra(fled by 

 the magnet in its natural ftate, it becomes magnetic after being 

 heated red hot. It does not effervefce with acids. When expo- 

 fed to a low red heat for half an hour, whether in fragments 

 or in powdef , it Idfes 4 per cent, in Weight. It foftens at ^^ of 

 Wedgwood. Its fpecific gravity is 2.802. After being boiled, 

 in the ftate of fine powder, in ten or twelve parts of muriatic 

 acid, the infoluble refiduum amounted to 6$ per cent. 



I ANALYZED 200 grains of this whin, and found that it con- 

 tained, in 100 parts, 



Silex, _ - - - 46 , 



Argil, - - - 19 



Oxyd of iron, - - 17 



Lime, _ _ - _ 8 



Moifture, and other vol. matter, - 4 



Soda, about - - - 3*5 



Muriatic acid, about - - 1 



98-5 

 ANALYSIS 



