338 Dr. Thomas Thomsons 



or oxydizing flame ; but the assay assumes the appearance 

 of enamel, just as when fused with carbonate of soda. 

 The constituents of this mineral are, 



Atoms. 



Silica, 41-42 20 71 8-8 



Magnesia, . . . 23-53 9-41 4 



Soda, 6-25 1-56 0-66 



Alumina, .... 4-47 1-98 0-84 '<_ 



Oxide of cerium, . . 3-57 0-40 0'17 

 Peroxide of iron trace, — — — 

 Water, 19-86 17-05 7-23 



] 



99-10 

 From these constituents, we may deduce the following 

 formula for its constitution, 



4 Mg m + (f Al + J- Cr) SU + NS* + 7 Aq. 

 No known mineral species agrees with this formula in its 

 constitution. Were it not for the presence of NS 2 it might 

 be considered as differing only from precious serpentine, 

 by containing twice the quantity of water that enters into 

 the constitution of that mineral. At all events, Dewey lite 

 must constitute a new mineral species. 



V. — AMPHODELITE. 



This name has been given by Nordenskiold to a mineral 

 found by him in the limestone quarry of Lojo, in Finland ; 

 and Berzelius gives a short description of it, together with 

 its analysis by Nordenskiold, in his Jaresbericht for 1833, 

 p. 174. Last year I received a small specimen of a mineral 

 from Dr. Holmes, of Montreal, which struck me as resem- 

 bling the amphodelite of Nordenskiold, so far as I could 

 judge from the description of Berzelius. The locality was 

 Bytown, Upper Canada. 



The specimen was an amorphous mass not much exceed- 

 ing the size of a pigeon's egg. I could detect in it no cleav- 

 age, nor any appearance of crystallization ; while in Nor- 

 denskiold's specimen two cleavages could be observed meet- 

 ing at an angle of 94° 19'. 



The colour of this mineral was partly white and partly 

 light rose red, distributed unequally, and running gradually 

 into each other, so as to leave an uncertainty where the one 



