Mineralogy — Geology. 371 



13. Analysis of Marmolite from New Jersey. By Mr Thomas Steel, 



ji Pupil of Dr Thomson's. 

 Silica, - - 41.256 



Magnesia, - - 41.720 



Alumina, - - 1.000 



Peroxide of iron, - 0.400 



Water, - - 17.680 



102.056 



Hence Dr Thomson considers it a hydrous sesquisilicate of magnesia, 

 or a variety of the precious serpentine or picrolite of Haussmann. Mr 

 Nuttal, the discoverer of the mineral, found no alumina, and made the 

 silica and the magnesia 36 and 46. 



14. Analysis of Bismuth blende of Breithaupt. By Professor Hunefeld. 



Carbonate of bismuth, - 58.8 



Arsenic acid, - - 2.2 



Silica, - - - 23.8 



Arseniate of cobalt, copper and iron, 5.9 

 Matrix, . - - 9.1 



99.8 



15. Analysis of Leelite. By Mr R. Mitchell, a Pupil of Dr Thomson's. 



GEOLOGY. 



16. Conclusion of the General Summary of the Geology of India, By 

 James Calder, Esq. From p. 184 of this volume. — " At Bancora," says 

 Mr Calder," the calcareous concretion called kunkur begins to cover the sur- 

 face of the granite and mica schists. Thence we pass on to the great coal 

 field that occupies both sides of the river Dummoda. The boundaries of 

 this formation have not yet been accurately ascertained ; to the southward 

 we trace its associating rocks (sandstone and shales) to within a few miles 

 of Rogonauthpore, reposing on granite. About forty miles north by east 

 from that place, we come to the first colliery ever opened in India. The 

 late Mr Jones, an enterprizing and laborious engineer, had the merit of 

 commencing these works in 1815, at a place called Rany Gunge, on the left 

 bank of the Dummoda. It is described as the N. W. coal district of Ben- 

 gal. Mr Jones observed the line of bearing for sixty-five miles in one di- 

 rection, its breadth towards Bancora (on the S. W. side) being not more 

 than eleven or twelve miles from the river ; and he conjectures that the 

 same coal formation, crossing the valley of the Ganges near Cutwa, unites 

 with that of Sylhet and Cachar, which he denominates the N. E. coal dis- 

 trict, and from which abundant specimens of coal have been produced. 



