162 Re- examination of Microlite and Pyrochlore. 



lie oxides, could be detected. The weight of mixed oxides, by 

 difference, -320 --099 = -221. 



E. On evaporating the fluid, which had given the precipitate 

 of D, with a little oxalate of ammonia, a white precipitate was 

 obtained. Heated with sulphuric acid to bright redness, 0-200 

 of pure sulphate of lime was left. Binoxalate of ammonia was 

 added to the ammoniacal fluid of O, and by evaporation the white 

 oxalate became granular. Separated by a filter, well washed, and 

 converted into a sulphate, at a red heat, its weight, when cold, 

 was 2-417. These sulphates were dissolved in 2000 grains of 

 boiling water, without any residue. In the solution, ammonia 

 afforded no precipitate ; an excess of carbonate of ammonia would 

 remove the whole of the base, as a granular precipitate, insoluble 

 in oxalic acid. The solution, by evaporation, would afford crys- 

 tals of sulphate of lime. The united weight of 2-417 and 0-200 

 =2-617, or the equivalent of 1-087 lime. 



F. The insoluble heavy powders of B and C, weighed -350 ; 

 treated with hydrochloric acid and water, were boiled ; there re- 

 mained undissolved a white powder, which was nearly pure co- 

 lumbic acid, weighing -060. Ammonia was added to the solu- 

 tion, and an excess of sulphydrate of ammonia was digested on 

 a black precipitate, which appeared. The fluid filtered off, was 

 evaporated, and the residue calcined. There remained a nearly 

 white peroxide of tin, weighing -070. The black sulphuret was 

 dissolved in cold diluted nitric acid, and afforded a colorless solu- 

 tion, which could be rendered neutral by ammonia. In it, chro- 

 mate of potash would give a yellow precipitate; sulphuric acid, 

 a white heavy powder ; metallic zinc separated brilliant gray 

 scales of lead. The weight of the sulphate of lead, by differ- 

 ence, was -220, or the equivalent of -160 of oxide of lead. 



Ten grains of the microlite have thus afforded, of 



Columbic acid, A and F, 7-960 



Lime, E, 1-087 



Oxides of uranium and manganese, D, - 0-221 

 Oxide of iron, D, 0-099 



Oxide of lead, F, 0-160 



Peroxide of tin, F, 0070 



Loss, 0-403 



In this analysis, the columbic acid and lime have been carefully 

 separated and weighed. The absence of y ttria is proved, not only 

 by trials in O and E, but by repeating the experiments described 



