1824.] Scientific Notices — Mineralogy. 73 



two alkaline bases, which are a mixture in some cases of potash 

 and soda, in others of potash and Hthia. Magnesia also exists 

 in most specimens, but does not appear to be so essential an 

 ingredient as the preceding. Oxide of iron is sometimes pre- 

 sent in a very large proportion ; sometimes it is altogether 

 wanting. 



The rubellite, from Rozena, in Mahren, consists, according to 

 his analysis, of 



Boracic acid . , 5*744 



Silica 42-127 



Alumina 36-430 



Oxide of manganese 6-320 



Lime 1-200 



Potash 2-405 



Lithia 2-043 



Volatile matter 1-313 



97-582 



This mineral does not contain a trace of soda. The substance 

 which Klaproth and Bucholz mistook for that alkali was in fact 

 a mixture of boracic acid, potash, and lithia. 



The schorl from Eibenstock, in Saxony, which was more 

 recently analyzed by Klaproth, consists, according to Gmelin, of 



Boracic acid 1-890 



Silica 33-048 



Alumina 38-235 



Protoxide of iron 23-857 



Soda with potash 3-175 



Lime with traces of magnesia 0*857 



101*062 



The tourmalines examined by him were six in number, and 

 were all from different localities. — (Schweigger's Journal, vol. 

 xxxviii. p. 514.) 



6. Petalite. 



Dr. Bigsby has discovered Petalite on the north shore of 

 lake Ontario, on the beach in front of York, the capital of 

 Upper Canada. It is a rolled mass weighing about a ton. The 

 mineral has been examined by Dr. Troost ; it occurs in crys- 

 taline masses, of a greyish white colour, with a tinge of green, 

 and resembles some varieties of Tremolite, for which indeed it 

 was first taken. — (See Jour. Acad. Nat. Sciences, No. 8, vol.3.) 



7. New Localities of American Minerals. By John W. Webster, 



MD. MGS. Lond. 

 Zircon and Green Felspar of Beverly (Mass). In a former 



