120 Want of Identity hetiDeen Microlite and Pyrochlore. 



fused mass for upwards of half an hour, until every thing solu- 

 ble was taken into solution. A dense, white powder remained 

 undissolved. 



B. Hydrosulphate of ammonia produced, in a portion of the 

 solution A, a precipitate, without sensible discoloration, and 

 which, from former proofs in my paper of 1835, was taken for 

 yttria. The remainder of the fluid was then precipitated by ox- 

 alate of ammonia, the precipitate ignited, redissolved in hydro- 

 chloric acid, the yttria thrown down by ammonia, and the lime by 

 oxalate of ammonia, which on ignition^ weighed 0.032 or 1.49 

 per cent.* 



C. The white, insoluble matter A, was digested for some time 

 in a saturated solution of hydrosulphate of ammonia, the opera- 

 tion being conducted on a filter in the way recommended by Ber- 

 ZELius. The insoluble matter was blackened by the afl"usion of 

 the hydrosulphate. 



D. The sulphohydric fluid was decomposed by nitric acid and 

 heat ; hydrochloric acid was added; no precipitation ensued. But 

 the fluid, on the addition of ammonia, aff"orded a precipitate of 

 peroxide of tin, which after ignition, weighed ,001, which equals 

 0.047 per cent. The oxide was reduced with carbonate of soda 

 on charcoal, to the metallic state. 



E. The blackened powder C was treated with dilute hydro- 

 chloric acid, and gently warmed. The filtered solution was pre- 

 cipitated by ammonia, and ignited. The peroxide of iron was 

 apparently blended with traces of yttria. It weighed 0.022 or 

 about I per cent. 



F. The insoluble matter, washed by hydrochloric acid (E) was 

 drenched upon the filter, with an abundance of hot water: it show- 

 ed no tendency to pass through the filter in a milky state, as titanic 

 acid is well known to do, under such circumstances. It was ig- 

 nited in a platina crucible, and exhibited a white color while hot, 

 as well as after cooling. Its weight after some accidental losses, 

 was 1.052 gr. = 49.11 per cent. But I still regard my former de- 

 termination of the proportion of acid, and which was 75.70 per 

 cent., to be very near the truth. 



* The calcareous content here obtained is quoted only as an approximation ; but 

 falling so much below what I previously found, and considered in conjunction 

 with my observation of implanted calcareous spar upon the crystal, it is possible 

 that lime may yet prove to be an accidental ingredient in the mineral. 



