470 ANALYSIS OP GREEN-SAND. 



Silica 49.83 



Alumina 6.00 



Magnesia 1.83 



Potassa 10.12 



Water 9.80 



Protoxide of iron 21.53 



Loss 89 



100.00* 



"Prof. Wm. B. Rogers found in the green-sand of Virginia 



Silica 51.70 



Protoxide of iron 25.20 



Potassa 10.33 



Water 10. 



Magnesia, a trace 



97.23f 



" The foregoing may be taken as a fair exhibition of the composition of 

 the green particles in green-sand ; and the following analyses may serve to 

 show the constitution of such chlorites and mica as may be presumed to be 

 most analogous to the green substances in the earth under consideration. 

 M. Vauquelin found in the green-earth of Verona 



Silica 52.00 



Magnesia 6.00 



Alumina 7.00 



Protoxide of iron 23.00 



Potassa 7.50 



Water . 4.00 



99.50J 



"Dr. Thomson found in the chlorite-earth, from the highlands of Scot- 

 land 



Silica 48.166 



Magnesia . . . 2.916 



Alumina 16.851 



Oxide of iron . , 19.000 



Potassa "6.558 



Lime 2.675 



Water 2.350 



98.718g 



" The composition of the most common silvery mica from Zinwald (Bohe- 

 mia) was ascertained by M. Klaproth to be the following 



Silica % 47.00 



Alumina . 20.00 



Potassa 14.50 



Ox. iron 15.50 



Ox. manganese 1.75 



98.75|| 

 "Having described the grounds on which I arrive at the conclusion that 



* American Journal of Science, vol. xvii., p. 277. 

 j- Farmers' Register, vol. ii., p. 181. 

 J Shepards' Mineralogy, vol. ii., p. 225, 

 | Idem, ii., p. 225. 



|j Idem, ii., p. 41, 



