Analysis of Indian Ores of Manganese. 277 



we might explain the simultaneous existence of silica and 

 sulphuretted hydrogen in the principal sulphurous waters. 

 This hypothesis is in some measure confirmed by the inte- 

 resting observations of M. Descloizeaux, which shew that the 

 siliceous springs of the Geysers of Iceland contain a large 

 quantity of sulphuretted hydrogen. 



I content myself with submitting these considerations to 

 geologists, merely observing that in explaining the formation 

 of sulphurous and siliceous waters by the decomposition of 

 the sulphuret of silicon, I am only extending the ingenious 

 theory proposed by M. Dumas, to explain the formation of 

 boracic acid. 



The sulphurets of boron and aluminum were prepared like 

 the sulphuret of silicon, and are likewise decomposed by 

 water. 



The sulphuret of magnesium I obtained by passing sul- 

 phuret of carbon over pure magnesia ; in this case the pre- 

 sence of charcoal does not appear to be of any use. This 

 sulphuret crystallises, and is soluble in cold water. When 

 its solution is kept at the ordinary temperature, there is but 

 a feeble disengagement of sulphuretted hydrogen ; but when 

 heated to ebullition, a lively effervescence of sulphuretted 

 hydrogen takes place, and there is an immediate deposition 

 of magnesia. 



Analyses of Indian Ores of Manganese, and of some Scot- 

 tish Zeolites. By Dr A. J. Scott, H.E.I.C.S. Commu- 

 nicated by the Author. 



Among a number of minerals which were kindly sent to 

 me by Dr Alexander Hunter of Madras from different loca- 

 lities in India, I have examined several during the course of 

 last winter in the laboratory of Dr Anderson of Edinburgh, 

 and under his immediate superintendence. Those which 

 present most interest in a mineralogical point of view are 

 two manganese ores found at Vizianagram and Bimlapatam, 

 in the northern Circars. It would seem that the former 

 occurs in very large quantities. A description of it by Dr 



