250 ON THE AUTOMALITE. 



being too small for an analysis, in which the propor- 

 tions are to be determined. 



It was first reduced to an impalpable powder, then 

 boiled for several hours in sulphuric acid, which ex- 

 erted a considerable action upon it ; the soluble part 

 was then separated from the insoluble by filtering. 

 To the soluble part, ammonia was added in great ex- 

 cess, and the solution filtered. The precipitate was 

 tinged with a yellow colour, produced by oxide of 

 iron. It formed alum with sulphuric acid and pot- 

 ash, and hence contained al limine. The ammonia- 

 cal liquor by evaporation threw down a white sub- 

 stance, soluble in ammonia, precipitable when the 

 excess of ammonia was saturated by an acid, and in 

 short presenting all the characters of oxide of zinc. 



Note — After the foregoing account of the Auto- 

 malite had been sent to the Academy, I met with the 

 second number of the New York Medical and Physi- 

 cal Journal, containing Thomas Nuttall, Esq's. 

 "Geological and Mineralogical Uemarks on the 

 Minerals of Patterson, and on the valley of Sparta," 

 in which I find he notices the Automalite of Franklin, 

 under the synonyme of Gahnite. The only difference 

 between his description and my own of sufficient im- 

 portance to be uoticed, is his having observed that 

 the edges of one of the basis of the octahedrons is 

 more commonly truncated than the other basis, a fact 

 all important in the consideration of crystals, as pre- 

 senting an anomaly not hitherto observed in the re- 

 gular octahedron, and which would in itself have 



