-344 Mr. Gee 0011*8 Experiments on a mineral Substance 
Uran-glimmei\ 
I shall add a few desultory remarks upon the yellow and 
green crystals, which frequently accompany this fossil. 
I considered them to be the two species of Uran-glimmer, 
which had been examined by the celebrated Klaproth. 
The yellow cubic crystals are light. Their specific gravity, 
taken at temperature 45 0 Fahrenheit, was 2,19. 
Exposed to the flame of the blowpipe on charcoal, they 
decrepitate violently. A piece of this substance is taken up by 
phosphate of ammonia and soda, without effervescence, and 
communicates a light emerald-green colour to the fused globule. 
By exposure to a red heat, this substance loses nearly a 
third part of its weight. It then becomes of a brassy colour. 
It is soluble in the nitric and muriatic acids : but I could pro- 
cure no crystallized salt from the solution of either of them. 
By evaporation to dryness, and redissolving the mass, some 
silica is separated. 
A. 
( 1 . ) A certain quantity of the yellow crystals were dis- 
solved in nitric acid. Muriatic and sulphuric acids successively 
dropped into the solution produced no sensible change. The 
contents of the solution were precipitated by ammonia, in white 
clots, mixed with some of a yellowish hue. Ammonia, added 
in excess, betrayed no sign of the presence of copper. 
( 2 . ) The ammonia, on evaporation, was found to have held 
a portion of the mineral in solution. A fresh portion of am- 
monia dissolved more, but in a less quantity, at each succeeding 
affusion of it. 
(3.) The precipitate, which had resisted the ammonia, was 
boiled in a silver crucible, with a solution of potash in alcohol, 
