404 Dr. Tliomas Thomson and Dr . SteeVs [June 



several years ago from a German mineral dealer. He 

 stated that he had accidentally observed it in a collection of 

 minerals in Sweden, from the proprietor of which he pro- 

 cured it, and that its original locality was not certainly 

 known. It weighed several ounces. 



It was an amorphous mass, having a very deep green 

 colour, so as to appear to the eye almost black. 



The lustre on the fresh fracture was vitreous and splen- 

 denti But when broken in certain directions it presented 

 a surface almost dull, and having a whitish aspect; but 

 when viewed through a microscope no extraneous matter 

 could be observed. The colour and want of lustre was 

 probably owing to long exposure to the air, which had 

 acted through certain natural rents in the mineral. For it 

 broke with much more facility, so as to exhibit the dull 

 than the splendent surface. 



Hardness 6*5; specific gravity at 60° from 4*1493 to 

 4-1795. The mean was 4-1607. 



Its other characters being the same as those of common 

 gadolinite need not be described here. Twenty grains, by 

 ignition, acquired a brownish colour, and lost 0*198 grains 

 of weight, or almost one per cent. This loss was doubtless 

 owing to the escape of water. 



During the pounding of the mineral for analysis small 

 metallic looking grains were observed, which were carefully 

 picked out and submitted to the following examinations. 

 They were malleable, infusible before the blowpipe, not 

 acted on by muriatic acid, but dissolving slowly in aqua 

 regia. The solution had a deep orange colour, a .few 

 blackish grains remaining at the bottom. It afforded a 

 yellow precipitate with sal ammoniac and salts of potash 

 and was obviously platinum. From 120 grs. of the mineral 

 2*33 grs. of platinum were picked out. But the quantity 

 was found to vary in different pieces. 



We attempted to analyze gadolinite by the processes em- 

 ployed by Berzelius. But we found that the peroxide of 

 iron, which we had precipitated by benzoate of ammonia, 

 contained also glucina, from which we could not separate 

 it by means of benzoate of ammonia however carefully 

 added. This led us to a careful investigation of the pro- 

 perties of cerium, yttria, and glucina. The facts ascer- 



