E. MINERALOGY AND GEOLOGY. 119 



resentatives contain only 2 per cent, of organic matter, the 

 remainder being inorganic, consisting chiefly of carbonates, 

 which were most probably produced in the organism of the 

 plant from the sulphate of lime and magnesia of the sea wa- 

 ter. Enormous deposits of " millepora" limestone found in 

 Europe were caused by the agency of this group. A feature 

 of interest is the vast percentage of magnesia in some recent 

 formations, in certain cases amounting to 17 per cent., and it 

 is suggested that the formation of dolomitic limestone may 

 be closely related to this form as the active agent. 13 A, 

 March 1, 1872,94. 



BITUMINOUS SHALES IN AUSTRALIA AND INDIA. 



An extensive bed of bituminous shales has been discovered 

 eighty miles from Sydney, Australia, near to the western slope 

 of the Blue Mountains, and a large establishment has been 

 erected for the purpose of obtaining oil. The seam is hori- 

 zontal, and from five and a half to six feet thick, in stratified 

 sandstone. About one hundred tons of the slate are worked 

 up weekly. The crude oil first obtained is subsequently con- 

 verted into burning fluid, lubricating oil, etc. In that portion 

 of India, also, adjoining the mountains of Persia, principally 

 occupied by the cretaceous and tertiary strata, sufficient traces 

 of petroleum have been found to make it important to make 

 farther investigations. Petroleum has likewise already been 

 obtained in the vicinity of Gunda. 18 C, 1871, 752. 



MICROSCOPICAL COMPOSITION OF SLATE. 



Zirkel has been studying the microscopic constitution of 

 clay and roofing slate, and finds that these are not composed 

 simply of elastic and dialitic mineral constituents, nor of the 

 hardened and finely ground mud of pre-existing rocks, but 

 that they embrace within their texture microscopical crystal- 

 line and crystallized constituents which vary in amount, and 

 often play the principal part in the composition of the strata. 

 7 C, Mb., 1872, 128. 



ANALYSIS OF METEORIC SAND. 



A meteoric sand which accompanied a heavy rain-storm in 

 Sicily, on the 9th of March, 1872, has been reported upon by 

 Silvestri, who states that the sand strained out from the wa- 



