M. Scheerer's Observations on Elceolith and Nepheline. 



stance, with the brown one from Fredriksvarn, there was 

 scarcely a perceptible trace, while the white species from 

 the Ilmen Mountains and the nepheline from Monte Somma, 

 deposit a precipitate after some days' standing. Hydro- 

 chloric acid is probably a widely diffused constituent of vol- 

 canic minerals ; I have, for instance, found distinct traces of 

 it in Analcime. 



III. CHEMICAL FORMULA FOR THE ELJEOLITHS. 



From all the analyses above detailed, it results, to a cer- 

 tainty, that both elaeolith, as well as nepheline, must be con- 

 sidered as composed of 3 atoms silica, 2 atoms alumina, and 

 2 atoms alkali. The alkali, however, always consists of 4 

 equivalents of soda to one of potash ; calculated accordingly, 

 it should be thus : 



Silica 44*67 



Alumina . . . . 33*12 



Soda 16-12 



Potash .... 6'09 



100-00 



Here, however, no notice is taken of 1, the amount of 

 water, 2 the amount of hydrochlorates and sulphates. If 

 we take both into account, we find that the species of elseoliths 

 examined contain about from 0'5 to 2-0 per cent foreign con- 

 stituents, which must be proportionally subtracted from the es- 

 sential constituents. An elseolith would thus be composed of 



0*5 per cent, foreign 1 per cent, foreign 2 per cent, foreign 



constituents. constituents. constituents. 



Silica . . 44*45 44-23 43'79 



Alumina 32-95 32*79 32-46 



Soda . . 16-04 15-95 15*78 



Potash . 6-06 6-03 5-97 



99-50 99-00 99-00 



But according to the view which pre-supposed in elaeolith 

 4 at. silica, 3 at. alumina, and 3 at. alkali, adopting the for- 

 mula 



the three corresponding compositions should be 



Silica . . 41*58 41-36 40'94 



Alumina. 34-67 34-50 34-15 



Soda . . 16-88 16'80 16'63 



Potash . 6-37 6-34 6-28 



99'50 99-00 98*00 



