310 Scientific Notices — Mineralogy. [Oct. 



results, in Dr. Gmelin's opinion, prove such an affinity between 

 pinite and mica, in regard to chemical composition, that they 

 can no longer be considered as generically separate. " The 

 circumstance that pinite contains no fluoric acid cannot be con- 

 sidered as an essential difference, when it is observed that even 

 those varieties of mica which occur in primitive limestones, con- 

 tain very little of that acid, or are entirely destitute of it, accord- 

 ing to the experiments of H. Rose : fluoric acid ought not, 

 therefore, to be considered as an essential constituent of mica." 

 — Edin. Phil. Journ. 



Dr. Gmelin gives the specific gravity of pinite = 2*7575 at 

 46° ; according to Phillips, it is 2*98. 



9. Analysis of Cinnamon-stone, from Ceylon. 



Dr. Gmelin has confirmed the accuracy of Klaproth's state- 

 ment of the composition of the cinnamon-stone (Beitrage, vol. v. 

 p. 142) by a recent analysis conducted in a very different man- 

 ner. His results give its composition as, 



Silica 40-006 



Alumina 22*996 



Lime 30-573 



Oxide of iron 3-666 



Potash 0-589 



Manganese Trace 



Volatile matter 0-326 



98-156 



In the course of the analysis, Dr. Gmelin digested a precipi- 

 tate, which had been thrown down by caustic ammonia, in a 

 considerable excess of carbonate of ammonia. "The liquid was 

 separated by the filter from the undissolved part, and evaporated. 

 A white substance fell down. Considering the manner in which 

 this substance had been obtained, one might have taken it for 

 glucine, ittria, or zircon, but it was pure alumina ; and when 

 dissolved in sulphuric acid by digestion, and mixed with a little 

 ammonia, it crystallized entirely into alum. It follows, hence, 

 that when alumina is precipitated by means of carbonate of 

 ammonia, it is not advisable to add the latter in great excess ; 

 and that the common method used to separate glucine from 

 alumina does not yield it pure." — (Edin. Phil. Journ.) 



Mineralogy. 



1 0. Singular Form of Crystals of Sahlite. 



Prof. Silliman found, near Greenwood Furnace, in Munroe, 

 about 20 miles south of Newburgh, in a small excavation which 

 had been made in searching for iron ore, crystals of green 

 augite, of the variety called sahlite, in a rock principally com- 



