1 08 M. Scheerer's Observations on Elaeolith and Nepheli?ie. 



in my analyses, we then obtain only about 1 1 per cent, soda 

 and 4 per cent, potash, which gives a loss of 4*5 for the 

 whole. Between C. G. Gmelin's analyses and mine there 

 prevails a satisfactory coincidence ; only the silica of the 

 former should perhaps be somewhat greater, as the small quan- 

 tities of it which constantly accompany the other constituents 

 were not separated and added to the main quantity. That M. 

 Gmelin did not redissolve the silica in carbonate of soda can 

 scarcely have given rise to any inaccuracy, as on employing 

 good pieces of this elaeolith the silica is always found free 

 from foreign ingredients. Likewise in the amount of alkali 

 this analysis differs slightly from mine, but this undoubtedly 

 arises from the method employed by him being less perfect 

 than the one now in use for the determination of potash and 

 soda. The sums of the chlorides agree on the other hand per- 

 fectly ; Gmelin obtained 39*1 percent, and I very nearly 39*0, 

 which proves that only the relative quantities of potash and 

 soda were somewhat inaccurately determined in Gmelin's ana- 

 lysis. 



3. Brown Elceolith from the same locality. — This variety 

 has not, as far as I am aware, been hitherto analysed, as it was 

 always considered to be a modification of the green elaeolith, 

 which is fully confirmed by the following analyses. I am in- 

 debted to the kind aid of Mr. W. Francis for analysis 6, made 

 in the laboratory of Professor H. Rose : — 



6. 7. 



Silica 45-51 45*55 



Alumina ~\ „„ f ^ 32*00 



Peroxide of iron J 1*41 



Lime 0*81 trace. 



Soda 15*86 16*09 



Potash .... 4*50 5*02 



Water .... 0*78 



100*21 100*85 



The specific gravity was found to be 2*61. 



4. White Elceolith from the llmen Mountains in Siberia. — 

 The occurrence of this mineral has been described by Pro- 

 fessor Gustav. Rose*. 



The llmen mountains consist for the greatest part of a rock 

 of white felspar, black uniaxal mica, and nepheline, thus ex- 

 hibiting, but far more so from the other minerals it contains, 

 such as zircon, pyrochlor, &c, great similarity to the zircon- 



* Fogg. Annular, vol. xlvii. p. 377. 



