330 t^^of. Gmdin^s Analyses. 



" This mica has a beautiful rose red colour, and occurs near 

 Penig, in Saxony, together with amblygonite, topaz, albite, 

 schorl, &;c. 



" Most of the minerals that occur in this place contain 

 lithion ; as for instance, a fine variety of quartz, lithomarge, 

 andalusite, &c. 1 shall publish the analyses of all these 

 minerals in the Edinburgh Philosophical Journal, and it will 

 give me much pleasure to send you specimens of each. 



" While on this subject, allow me to say that 1 have discov- 

 ered a very useful test for lithion, before the blowpipe : viz» 

 the flame assumes a very fine purple colour — but the flame 

 of an oil lamp should be used, and not that o) a tallow can- 

 dle. By means of the latter the colour of the flame is not so 

 decided. 



'' By an analysis of Helvin, a very scarce mineral, 1 have 

 liscovered glucine to be a constituent of it. It consists of 



"' The Latrobite of Mr. Brooke (Diploite of Bresthaupt) is 

 composed, according to my analyses, of 



Silica, . . I . 44.653 



Alumina, . . - - 36.814 



Lime, ..... 8.291 



Ox. of manganese, - - 3.160 



Manganese with ox. of manganese, 0.628 



Potash, . - - = 6,575 



100.000 

 Sain. .121 



