ANALYSIS. 257 



tate, I dropped upon it fotne fulpburic acid. No fumes were Defciiptiouand 

 perceptible. The fulphate of lead was feparaled by the filler, ^{Jjf"j f^^Jn 

 and the clear fluid, which palTed through it, was gradually Cornwall, 

 evaporated; fmall cryftallizations were formed, the figure of 

 which I could not afcertain ; fome of them were expofed to 

 the flame of the blowpipe in a gold fpoon ; they did not burn 

 to coal, nor give out any empyreumatic fmelj por fufe, but 

 tbey afllumed an earthy appearance *, 



Uran-glimmer. 



I ftiall add a (ew defultory remarks upon the yellow and 

 green cryftais, which frequently accompany the foffil. 



I confidered them to be the two fpecies of uran -glimmer 

 which had been examined by the celebrated Klaprolb. 



The yellow cubic cryftais are light. Their fpecific gravity, 

 taken at temperature 45" Fahrenheit, was 2,19. 



Expofed to the flame of the blowpipe on charcoal, they 

 decrepitate violently, A piece of this fubftance is taken up by 

 phofphate of ammonia and foda, without effervefcence, and 

 communicates a light emerald. green colour to the fufed 

 globule. 



By expofure to a red heat, this fubflance lofes nearly a 

 third p^ of its weight. It then becomes of a brafly 

 colour 



It is foluble in the nitric and muriatic acids ; but I coulcj 

 procure no cryftallized fait from the folution of either of 

 them. 



By evaporation to drynefs, and rediflTolving the mafs, fome 

 iilica is feparated. 



A 



(1.) A certain quantity of the yellow cryftais were dif^- 

 folved in nitric acid. Muriatic and fulphuric acids fuccef- 

 fively dropped into the folution produced no fenfible change. 

 The contents of the folution were precipitated by ammonia, 



• I fubjefted fome of the Barnftaple mineral, with which Mr, 

 Raflileigh kindly furnithed me out of his cabinet, to experiment^ 

 with a view of afcertaining whether it would produce x,he fame 

 volatilized falijie criift, as the ftenna gwyn fclfil, and I foupd thai 

 it (}id. 



in 



