54 Proceedings of the Roi/al Irish Acadeno/. 



lilr. Early's analysis of the mineral agrees in all essential paiiicu- 

 lars witt those of Kammelsberg and von Kobell, though both those 

 distinguished observers found slightly more iron in the ferric con- 

 dition. A comparison of the analyses of different specimens of Liev- 

 rite by Rammelsberg, von Xobell, Stiideler,* and Early prove that 

 there is Kttle variation in the proportion of EeT," to Ee"; I am there- 

 fore disposed to regard the foimer as an essential constituent of the 

 mineral, rather than as a product of the oxidation of a calcio-feiTons 

 silicate. That the mineral oxidizes in time there can be no doubt ; 

 but I have had a number of specimens of Lievrite under observation 

 for nearly ten yeai's, and though t"^o of them "svere placed in a rather- 

 damp case, they suffered comparatively slight superficial oxidation. 



If, then, -^-e admit that Lievrite is essentially a diealcic-ferroso- 

 ferric silicate, we can assign to it the following symmetrical formula : — 



(EeYO)^ 

 ^ 



This formula has at least the merit of indicatiag that the function, 

 of the ferric group is probably one of considerable importance, and 

 that, so far from being regarded as an accidental constituent of the 

 mineral, it ought to" be considered one of the most important com- 

 ponents of the molecule of the compound. 



- See Dana's " System of Mineralogy," 5th edition, p. 296. 



