408 



Z)r. Thomas Thomson on the 



the same locality discovered by Nordenskjold, and likewise 

 analyzed by Berzelius, constitutes a fourth species.* I pro- 

 pose in this paper to give a short account of the characters 

 and chemical constitution of these four species. 



1. Torr elite. 



I give this name to the new species, which I have just 

 received from New York, by the liberality and kindness 

 of Dr. Torrey. I haVe been induced to name it after my 

 much respected friend, as a slight acknowledgment to him 

 for the many interesting and new minerals with which he 

 has from time to time favoured me.f 



Torrelite has been found lately in a granite rock at 

 Middleton, in the state of Connecticut, where it is occa- 

 sionally disclosed by the workmen, who are blasting out 

 felspar for a porcelain manufactory. 



It occurs most commonly in irregular masses about the 

 size of a filbert ; though occasionally, as appears from a 

 fragment of a crystal in my possession, it is crystallized. 

 The figure in the margin represents this 

 fragment. It is a four sided prism, the 

 base of which, P, is so rough and irre- 

 gular, that we cannot decide whether it 

 forms a right angle with the faces of the 

 prism. The longitudinal faces of the 

 prism are sensibly equal. The edge 

 between M and T is re-placed by a narrow 

 face a. The only measurements that I 

 could make are the following : 



M 



M on T (mean of 5 trials) 

 T on a (mean of 3 trials) 

 M on « (mean of 3 trials) 



84° 20' 

 152° 

 110° 20' 



* Afhandlingar, vi. 237. 

 t The name Torrelite has.been already given by Professor Ren wick to a mineral 

 of a Vermillion colour, which he subjected to analysis, and which he found to 

 contain oxide of cerium , but which was afterwards examined by Mr. Children and 

 Mr. Faraday, without their being able to discover any cerium (see Annals of 

 Philosophy, 2nd series, ix. 217 and 221). Ten years having elapsed since these 

 experiments were made, and no mineralogist, so far as I know, having noticed Mr. 

 Renwick's torrelite, I take it for granted that its claims to rank as a new species 

 have not been admitted. 



