114 M. Scheerer's Observations on Elceolith and Nepheline. 



stance, with the brown one from Fredriksv'arn, 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 elaeoliths 

 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 elaeolith would thus be composed of 



1 per cent, foreign 2 per cent, foreign 



constituents. constituents. 



44-23 43-79 



32-79 32-46 



15-95 15-78 



6-03 5-97 



0-5 



per cent, foreign 





constituents. 



Silica . 



. 44*45 



Alumina 32-95 



Soda . 



. 16-04 



Potash 



. 6-06 



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 



jg{ S i + 3Aisi; 



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 



