July, 1846.] Proceedings of the Asiatic Society. lxiii 



The few fragments I obtained were angular. 



The mineral is opaque, the streak a dirty white inclining to orange -grey. It does 

 not soil. The hardness of the purest mineral I find to be S — 6 as compared with 

 Apatite and Adularia. 



It is rather tough and there is a slight adherence to the tongue. It feels mea- 

 gre and cold ; the specific gravity is very uncertain, and, in truth, no datum at all, 

 for the mixture of galena and chert is so considerable that we have no piece which 

 would give even an approximation to the correct determination of this character. It 

 rings a little, I think, when struck with the hammer, and when breathed on gives a 

 strong clayey smell. When pounded it is easily reduced to an impalpable powder 

 of a yellowish-fawn or rosy-buff colour. 



Blowpipe Examination. 



A portion of the darker red crystallised part in the forceps changes to a bright 

 chocolate brown, with a slight metallic or slaggy lustre in some parts, but does not 

 fuse — 



On charcoal it takes a greyish brown colour with a whitish dust about it in some 

 places — 



The powder fused with Soda on charcoal gives bright spots, and on Platina 

 wire effervesces and spits sharply. In the reducing flame, a dull, dirty greenish 

 white bead but nothing reduced from it — 



With Borax on platinum wire in small quantities a clear glass ; with more of 

 the mineral, a light clear emerald green glass, both in the reducing and oxidating 

 flame, which cools to almost a colourless one when quite cold — 



With Microcosmic salt on platina wire infusible ; when borax is added fuses to a 

 light green yellowish -white bead, becoming quite opaque and much less coloured 

 when cold. 



Via Hwmida. 



The mineral was found soluble with much effervescence in all the mineral 

 acids, but acetic acid had no effect upon it. 



The acid solutions, particularly that with sulphuric acid, gave abundantly with 

 potass the characteristic gelatinous and semi-crystalline precipitate of cerium ; 

 and it was found by the usual tests that it contained moreover iron, sulphuret of 

 lead, and lime, besides the usual accompaniment of silex and traces of alumina. 



It was dissolved in sulphuric acid, which took up the iron and cerium only, and 

 left the lead and lime as insoluble sulphates. No fluorine was detected by this or 

 by the blow pipe. The solution was almost neutralised by ammonia, and the iron 

 and cerium thrown down by benzoate of ammonia. It had been previously ascer- 

 tained that the benzoate of cerium was highly soluble, and thus when the mingled 

 benzoates were thrown on a filter they were easily separated by washing ; the inso- 

 luble benzoate of iron remaining on the filter. The benzoate of cerium was found 

 to crystallize in acicular plumose crystals, forming thin broad feather-like tufts and 

 groups. 



