1870.] Proceedings of the Asiatic Society. 283 



In one small piece I fonnd 2. 67 per cent, of matters insoluble in 

 nitro-muriatic acid, but generally it was very small. 



It will be observed that this sample differs from the first in the 

 smaller proportion of what may be considered accidental constituents, 

 and is a purer specimen of the essential constituents, arsenic, iron, 

 and copper. The inside pieces contained no sulphur : the outside 

 crust yielded a trace probably in the state of earthy sulphate. And 

 while the first sample contained a notable quantity of silver, this 

 did not appear to contain any, or at least so little that I could not 

 detect it in the amount of material at my disposal. The quantity 

 of antimony was also less than half that of the first sample. 



I have not been able to find in any book on Mineralogy I have had 

 access to a description of such a mineral. The nearest are Arseni- 

 cal Iron Pyrites (Mispiekel) and Axotomous Arsenical Iron. But 

 it differs from the former in the total absence of Sulphur, and from 

 both in the presence of a considerable quantity of Copper, as well 

 as in the larger proportion of Iron ; and it differs still more in the 

 proportion of the two basic metals together to the Arsenic, i\\Q 

 latter being small in proportion to the former. 



The constituents approximate, though not very closely, to 2 

 equivalents of Arsenic, 6 of Iron and 1 of Copper ; rather more than 

 6 of iron and less than 1 of copper. This can scarcely be reduced 

 to any probable atomic formula ; but if the proper metallic nature of 

 Arsenic be admitted it may be considered as an . alloy, and alloys 

 are not limited in their composition to definite formulas. The excess 

 of basic metals in its composition gives it a fixity under the action 

 of heat not very usual in arsenides or unoxidised arsenical com- 

 pounds. 



I would venture to propose for this mineral the name of O'Ri- 

 leyite in honor of the gentleman who sent it to me, whose services 

 have unfortunately been lost to the Indian Government by an un- 

 timely death. This notice may perhaps lead explorers of these 

 districts to discover additional specimens of this or analogous 

 minerals. 



