CONE-IN-CONE STRUCTURE. 327 



and the residue is black and powdery. More than one-half 

 of the ash consists of sulphate of lime, the other main con- 

 stituents being silica, alumina, and oxide of iron. Caustic 

 potash acts strongly on this substance, but alcohol and ether 

 have little or no effect. 



From the composition and physical properties it is clear 

 that this substance is a variety of brovrn coal. The banded 

 structure above referred to as occasionally visible is probably 

 due to the deposition of peaty matter in successive layers 

 rather than to actual woody structure. The high percentage 

 of sulphate of hme in the ash is of interest, and points to the 

 theory brought forward above being correct, as this salt is 

 frequently deposited from infiltrating waters. 



No microscopic examination either of the raw brown coal 

 or of its ash has yet been made. Both would be interesting, 

 the former to show if any traces of vegetable tissue still 

 survive, and the latter to show the presence or absence of 

 waterworn material. 



In conclusion, we would remark that this history of a 

 comparatively modern deposit of brown coal in the middle of 

 a hill of very old rocks may explain the occasional occur- 

 rences that have been at various times reported of anthracite 

 and graphite in reefs of quartz and their casings. Doubtless 

 in course of time, if circumstances were favourable, this, too, 

 would become more thoroughly carbonised. The quantity 

 of carbonaceous matter present in this instance is, however, 

 we believe, much larger than has ever been recorded in any 

 similar circumstances, "as it is to be reckoned by tons and not 

 by stray pieces. So much of it is distributed through 

 portions of the rock that there is little doubt that the whole 

 mass excavated from the Moonlight Company's drive would 

 smoulder for weeks if once properly set on fire. 



2.— ON A SAMPLE OF CONE-TN-CONE STRUCTURE, 

 FOUND AT PICTON, NEW SOUTH WALES. 



Bij A. J. SACH, F.C.S. 



The so-called cone-in-cone structure, which appears to be 

 found in most countries, and which consists either of impure 

 carbonate of hme or, less frequently, of impure carbonate of 

 iron, still awaits a satisfactory explanation as to its mode of 

 formation. It is more for the sake of eliciting the opinions 

 of the geologists now assembled than of advancing any 



