1884. ] 697 {Genth, 
molybdate. The excess of molybdic acid was removed by precipitating 
the slightly acid solution by nitrate of lead. The excess of lead and trace 
of molybdenum were precipitated by hydrogen sulphide, and from the 
filtrate the glucina, ferric oxide and alumina separated by sodium hydrate 
asin I. Iam afraid that a portion of the fluorine was lost in a similar 
way. The ignited calcium fluoride was treated with sulphuric acid and 
weighed as calcium sulphate, and, as probably a little silica was there 
which was volatilized as silicon tetrafluoride, it lost 1 per cent, and gave 
only 6.04 per cent of fluorine. 
III. 0.83808 grm. of the same material as I, was intimately mixed with a 
known quantity of freshly ignited plumbic oxide, and put in a small 
platinum crucible with close cover, this was placed in a larger plati- 
num crucible which had some magnesia in the bottom, it was then tightly 
covered and gradually heated to a strong red heat, which was continued 
for twenty minutes. After cooling the small crucible had sustained a loss 
of 0.0020 grm., which would represent 0.61 per cent. The contents of 
the crucible were completely fused and the lid showed a slight film. As 
lead fluoride is slightly volatile, it is a question whether this very small loss 
may not be owing to this, and that the mineral is anhydrous, 
The fused mass was dissolved in acetic acid and filtered, the residue, 
consisting mostly of lead phosphate and fluoride, was dissoived in diluted 
nitric acid. A pulverulent residue, containing amongst other substances 
calcium fluoride, was filtered off, the fluorine driven off by sulphuric acid 
and the sulphates added to the other portion of the analysis. It was 
found that a considerable portion of the lead phosphate had gone in 
solution, therefore all the liquids, from which the lead had been removed 
by hydrogen sulphide, were united and the analysis finished as under IT. 
IV. 0.5860 grm. of the very finely powered perfect crystals from an- 
other specimen with traces of albite was placed in a platinum crucible 
moistened with water, and then sulphuric acid was added and it was 
evaporated until copious fumes of sulphuric acid went off. It was dis- 
solved in water and hydrochloric acid. A very slight portion, 0.0070 
grm., escaped the decomposition and was therefore deducted from the 
original quantity. The solution was precipitated by ammonia which 
would precipitate all the glucina, alumina, ferric oxide and a part of the 
lime in combination, with all the phosphoric acid, and would leave the 
calcium which was in combination with the flourine in solution, I found 
that 13.16 per cent had not been precipitated, which corresponds to 8.93 
per cent of fluorine, which is probably more correct than 6.04 per cent as 
found by direct determination, The precipitate by ammonia was dissolved 
in nitric acid, the phosphoric acid precipitated by ammonium molybdate 
and the analysis finished as ahove. 
