1824.] Scientific Notices — Mineralogy. 46'9 



very cursorily, or he could not have erred so widely as he has in 

 arranging them under the heads in which they stand in his list. 

 Is he not aware that natrolite and mesotype are the same mineral, 

 and that the Kilpatrick mineral differs both from mesotype and 

 from nadelstein, and has received the designation of Thomsonite. 

 Had this list proceeded from less authority in these matters 

 than Dr. M. we should not have noticed its inaccuracies. But 

 we consider that by thus correcting it, we are rendering a service 

 to mineralogy. 



4. On the Pyro-electricity of Minerals. 



Haiiy gave the following list of pyro-electrical minerals, with 

 the names of those who first noticed their pyro-electrical pro- 

 perty : 



Tourmaline Lemery. 



Topaz Canton. 



Axinite Brard. 



Boracite, ~] 



Mesotype, 



Prehnite, )> Haiiy. 



Oxide of zinc, 



Sphene, J 



In 1817 and the following year, Dr. Brewster took up the sub- 

 ject, and made many experiments relating to it ; and although 

 want of leisure prevented his extending it so far as he had ori- 

 ginally intended, the results he has furnished us with are too 

 interesting not to induce us to hope that he will yet find oppor- 

 tunities of pursuing it himself, instead of delegating it to other, 

 and probably less able hands. 



His method of determining the existence of pyro-electricity 

 of weak intensity, in various minerals, is as follows : — " I 

 employed the thin internal membrane of the Arundo P/i rag- 

 mites, which was cut with a sharp instrument into the smallest 

 pieces. These minute fragments were well dried, and the pyro- 

 electricity of any mineral was determined by its power of lifting 

 one or more of these light bodies, after the mineral had been 

 exposed to heat. I used also a delicate needle of brass, the 

 pivot of which moved upon a highly polished cap of garnet, and 

 which was affected by very slight degrees of electricity. 



" In this way I determined the pyro-electricity of the follow- 

 ing minerals : 



Scolesite,* Diamond, 



Mesolite,* Yellow orpiment, 



Greenland mesotype, Analcime, 



Calcareous spar, Amethyst, 



• It is probable that the mesotype of Haiiy was one or other of these two mineral*. 



