ORTHITK. 133 



It is soluble in three times its weight of water at a tem- 

 perature of 12 R. It melts and deflagrates upon glowing 

 charcoal, but not so violently as the prismatic Nitre-salt. 

 If rubbed in an isolated state, it acquires a very strong 

 negative electricity. It consists of 



Nitric Acid 54-97- 



Soda 45-03. 



according to BERZELIUS' formula, Na N 2 . 



It is found in Peru, in the district of Atacama, near the 

 seaport of Yquique, and according to MARIANO DE RIVERO, 

 occurs with clay in beds of different thickness, extending 

 more than fifty miles, and is worked to great advantage. 



NUTTALLITJ:. 

 Nuttallite. BROOKE. Ann. of PhiL XLI. p. 366. 



Crystals, right square prisms, imbedded in calca- 

 reous spar. Resembling Scapolite, but softer 

 and more glassy in the fracture. Play of light 

 similar to that of Elaolite upon the faces of the 

 prism. Colour grey. 



OETHITE. 



Orthit. BERZELIUS. Afh. i Fysik, &c. Vol. V. Orthite. 

 PHILL. p. 265. 



Form, long and straight acicular masses. Massive : 



composition impalpable. Fracture conchoidal. 

 Lustre vitreous. Colour ash-grey, passing into 



brown, if the mineral be decomposed. Streak 



brownish-grey. Opake. 

 Scratches glass, though with difficulty. Sp. Gr. 



= 3-288, BERZELIUS. 



