Intelligence and Miscellanies. 205 



to two inches in length, none of which are composed of con- 

 tinuous masses, but are often interrupted by fissures and oc- 

 casionally corroded or broken off. They are white of a vi- 

 treous lustre and transparent except at their termination up- 

 on the surface, where they are opaque from the loss of water 

 of crystallization. The specimens from the latter spot, on 

 the other hand, present a botryoidal surface like prehnite, 

 from which radiate perpendicularly, perfectly straight and 

 almost inconceivable minute crystals, much resembling, ex- 

 cept that the fibres are shorter, some of the most delicate 

 Zeolites from the Giant's Causeway. The fineness of the 

 fibres which form these tufts communicates to them a degree 

 of silkiness like the native alum of Hurlet, near Paisley, in 

 Scotland, but they differ strikingly from this last in never 

 being curved, and in rarely being closely aggregated. 



Dr. Thomson finds the composition of the native soda 

 alum to be, 



3 atoms sulphate of alumine, - - 21.75, 



1 atom sulphate of soda, - - - 9.00. 



20 atoms water, .... 22.50. 



53.25. 

 and the only difference between it and the artificial soda 

 alum is, that the former contains 20 atoms of water, while 

 the latter contains 25 atoms. To this circumstance he at- 

 tributes their difference in crystallization, — the artificial soda 

 alum assuming the octohedron, whereas the native affects, 

 apparently, a quadrangular prism. 



Charles Upham Shepard. 



Y. C. March 22d. 



20. Proceedings of the Lyceum of Natural History of New 



York. 



(Continued from Vol. XV. page 360.) 



July, 1828. — Mr. Barnes made a report on the Helices 

 from the West Indies presented at a former meeting. He 

 stated that great difficulties existed in determining the Amer- 

 ican species, and that he had received many from the Car- 

 ribean seas of which he could find no descriptions in the 

 systems. — Dr. Mitchill submitted specimens of plants occa- 

 sionally sold in the shops for Digitalis. Mr. Halsey, to 

 whom it was referred for examination, reported it to be the 



