164 Re-examination of Microlite and Pyrochlore. 



was alkaline. Sulphydrate of ammonia was added, and the ves- 

 sel closed from the atmosphere. After twenty-four hours, a black 

 precipitate had separated from the fluid. This was collected and 

 calcined ; 670 of a red brown powder remained. By nitric 

 acid and. fusion with carbonate of soda, a green mass resulted. 

 Boiling water gave a greenish yellow solution, containing oxides 

 of uranium and manganese. There was left, after the action of 

 carbonate of soda, a red brown oxide of iron, which weighed 

 0-470. 0-670 --470 = -200, is the weight of the mixed oxides 

 of uranium and manganese. 



F. The fluid from E was evaporated to a dry salt, which was 

 heated in a platina vessel, allowing a current of air. When the 

 carbonaceous matter had been removed, a light yellow oxide re- 

 mained. When cold, the oxide was white, and possessed the 

 known characters of titanic acid. It weighed 4-040. 



G. In the fluid from C, binoxalate of ammonia gave a precip- 

 itate, which, converted into sulphate, weighed 7*547. When the 

 fluid from D was treated in the same way, 1-824 of sulphate were 

 obtained. These were dissolved in water, and proved to be pure 

 sulphate of lime, denoting 3-890 of lime. Twenty grains of 

 pyrochlore have thus afforded of 



Per 100. 



Columbic acid, - - - B and D, 10-620x5 = 53-100 



Lime, - G, 3-890 -19-450 



Titanic acid, - - - F, 4-040 =20200 



Oxide of iron, E, 0-470 = 2-350 



Oxides of uranium and manganese, E, 0-200 = 1-000 



Oxide of tin, ... O, 0030 ) _. n4n _ n . 9nn 



Oxide of lead, - - - D, 0010 £ ~ U4U ~ u ^ uu 



Volatile matter lost at redness, - - 0-160 = 0-800 



Loss, 0-580 = 2-900 



20 000 

 In the above analysis, I have very briefly described the pro- 

 cesses adopted for separating the constituents. I carefully exam- 

 ined the substances enumerated, and have been unable to discover 

 others, which would not have been lost by the method chosen. 



The following experiments have reference to the alkaline and 

 volatile constituents. Three grains of pyrochlore were digest- 

 ed in hydrochloric acid, contained in a platina capsule. Over 

 the fluid, a highly polished surface of glass was kept cool by wa- 

 ter. The powder dissolved entirely, without causing any loss of 



