34 PHYSIOGRAPHY. CLASS i. 



4. It occurs in the neighbourhood of Aussee, Ischel, and 

 Hallstadt in Austria, at Hallein in Salzburg, in Hun- 

 gary, in Switzerland, also in Italy and Spain. 



5. It is employed in medicine, and in manufacturing 



GENUS III. NITRE-SALT. 

 1. PRISMATIC NITRE-SALT. 



Prismatic Nitre. JAM. Syst. Vol. III. p. 35. Man. p. 8. 

 Nitre. Nitrate of Potash. PHILLIPS, p. 189. Naturli- 

 cher Salpeter. WERN. Hoffm. H. B. Th. III. 1. S. 216. 

 Salpeter. HAUSM. III. S. 849. Salpeter. LEONH. S. 

 629. Potasse nitrate'e. HAUY. Traits', T. II. p. 346. 

 Tabl. comp. p. 19. Trait^, 2de. Ed. T. II. p. 177. 



Fundamental form. Scalene four-sided pyramid. 

 P = 132 22'; 91 15'; 107 43'. Vol. I. Fig. 9. 

 HAUY. 



a : b ; c = 1 : V 2 ' 1333 : V 0-7H1- 



Simple forms. P co (o) ; P 1 (z) ; P (y) ; 

 P + 1 (t) ; P + oo (M) = 120 ; f r (x) - 111 

 12'; P r + 1 (P) = 72 IT; P r + 2 (*) = 40 

 7'; r + o>W; Pr + oo (/) 



Char, of Comb. Prismatic. 



Combinations. 1. Pr+ 1. P + QD. r + oo. Fig. 9. 



2. P. Pr+1. P+oo. fr + oo. 



3. P co. p r + 1. P+oo. Pr + QD. 



4. r. + 1. Pr + 2. P + co. Pr+cc. Fig.23. 

 Cleavage, P + co and f r + oo. Imperfect, the 



latter rather more easily observed than the former. 

 Fracture conchoidal, Surface, P + QD and Pr -f- GO 

 striated, both horizontally and vertically, particu- 

 larly in irregular crystals. 



