Finch on the Celtic Antiquities of America. 1 49 



According to this analysis, the essential constituents of 

 this niineral are Bisilicates, and its mineralogical formula is, 

 FS^+mg S^+2 CS'. 



The results of nny analysis differ materially from those 

 of Mr. Keating's, especially in the proportion of the Silica, 

 and in my having found Magnesia in this mineral.* 



The constituents of this mineral being Bisilicates, it can- 

 not, therefore, constitute a nezv species, but must necessarily 

 be ranked with the pyroxenes. Mr. Rose examined many 

 pyroxenes, in the laboratory of Professor Berzelius, and he 

 observes, that the analyses of different specimens show, 

 "that all minerals which have the crystalline form of py- 

 roxene are Bisilicates.'^''] This chemist does not consider 

 Magnesia essentia! in the composition of pyroxenes! ; when 

 treating of the ''Black crystallized pyroxene from Ta- 

 berg, in Wcrmeland," which yielded 4.99 per 100 of Mag- 

 nesia, he says expressly, " if the magnesia is not taken into 

 consideration, this pyroxene belongs to the second divis- 

 ion," viz. to that of *' pyroxenes with lime and protoxide 



ANTIQUITIES. 



Art. XX. — On the Celtic Antiquities of America. By 

 John Finch, F. B. S. Sic. Professor of Geology and 

 Mineralogy. 



From our earliest infancy we are accustomed to admire 

 every thing connected with ancient times. The sentiment 

 seems implanted in our nature, and if the monuments we 



* The proportions of the silica obtained from three different trials, were 

 per 100, Ist. 45.333— 2d. 45.000— 3d, 45.333. In my preliminary experi- 

 ments, the magnesia was detected, after the silica had been separated, by 

 treating the liquor with an excess of sub-carbonate of ammonia ; after sep- 

 arating the precipitate, the liquor was treated with ammonia, and phos- 

 phate of soda ; ammoniacal phosphate of magnesia was precipitated. 



t Annals of Philosophy, new series, for March 1823, p. 224:. 



% Annals of Philosophy for March 1823, p. 227. 



