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 ahd 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, ee 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. 
Cuarces Urnam SHEPARD. 
Y¥. C. March 22d. 
20. Proceedings of the sitet of Natural History of New 
ork, 
(Continued from Vol. XV. page 360.) 
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 
