in the Onondaga Salt-group at Syracuse, JST. Y. 141 



the melilite basalt of Hochbohl by hydrofluoric acid. The 

 method proposed by this latter investigator was therefore made 

 use of in the present case with complete success. The finely 

 powdered rock was digested for a long time in concentrated 

 hydrochloric acid under pressure, and all the components dis- 

 solved except the octahedral crystals and the mica. These 

 were separated by washing until finally a powder was secured 

 which the microscope showed was composed of the black and 

 yellow crystals in about equal proportions along with a small 

 amount of the brown magnesia mica. This powder, which was 

 found to weigh -0442 gr., was then treated with strong sul- 

 phuric acid, in which "0277 gr., of the chromite remained un- 

 dissolved. A quantitative analysis of the filtrate, containing 

 only '0165 gr., was kindly made for me by Mr. J. H. Kastle, 

 of the chemical laboratory of the University with the following 

 result : 



TiO a 34-54 



CaO .._ 12-12 



FeO 54-54 



101-20 

 This analysis can only be regarded as an approximation on 

 account of the extremely small amount of material at com- 

 mand. Mr. Kastle says that the iron is undoubtedly too high. 

 What of this substance is present is partly contained in the 

 perofskite, isomorphous with CaO ; partly derived from the 

 mica which is dissolved by sulphuric acid. The above pro- 

 portion of CaO puts the nature of the mineral as perofskite 

 beyond a doubt, as no other mineral is present which contains 

 a trace of lime. Moreover any other titanium mineral, as for 

 instance anatase,* would not have been completely dissolved 

 by sulphuric and hydrofluoric acids. 



Perofskite was first recognized as a rock constituent in 1876 

 by Borickyf in the nepheline basalt of Wartenberg in Bohe- 

 mia. In 1878, Hussak^: discovered it in the basalt lava of 

 Scharteberg in the Eifel, and in 1883, it was isolated and 

 analyzed from the melilite basalt of Hochbohl by Stelzner.§ 

 In all of these cases the crystals were simple octahedrons, and 

 Hussak describes them as doubly refracting, like most of the 

 larger crystals of this species. Sauer|| has recently described 

 large crystals showing the cube and octahedron in the coarse 

 veins of the nepheline-basalt from Wiesenthal in Saxony. 



* The suggestion was ventured in the preliminary description of the Syracuse 

 serpentine, published in '•Science" of March 11th, that these crystals might be 

 anatase. 



f Sitzungsber. d. bohm. Ak. d. Wiss., 1876. 



\ Sitzungsber. d. Ak. der Wiss. in Wien., April, 1878. 



§ Neues Jahrbuch fur Mineralogie, etc., II Beilage Bd., p. 390. 



jj Zeitschrift d. deutsch. geol. Gesellschaft, xxxviii, 1885, p. 441. 



