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Transactions of the Society. 



containing the sublimate, were examined under the Microscope. 

 The instrument revealed many minute, cryptocrystalline, stelliform 

 tufts connected in some cases by long, very slender bodies, which 

 I believe to be crystals of sublimation and perhaps those described 

 by Mr. Durand. 



Owing partly to the difficulty of decomposing this mineral by 

 heat, and partly to want of skill and practice, I made several 

 unsuccessful attempts to reduce it to its elements in a combustion 

 furnace. I then sent a sample to Dr. Ernst Huetlin, of Freiberg, 

 Germany, who had a high reputation as an organic chemist, and 

 received from him the following result, a mean of three deter- 

 minations : — 



Carbon, per cent 88*10 



Hydrogen „ 9-17 



97-27 



Mr. Durand thought his mineral might be some modification of 

 idrialite, which I have reason to doubt, and I have placed the 

 physical characters of the two minerals side by side for com- 

 parison. 



Idrialite. Aragotite. 



Carbon 94-9 88-10 



Hydrogen 5 - l 9-17 



Colour brownish black honey yellow 



Streak red white 



Hardness 15 10 



Specific gravity .... 1*5 11 



opaque transparent 



As far as I know, this is the first notice and examination of 

 this mineral since its discovery in 1872. 



