i 8-23 



54 Hillebrand — Analyses of Tysonite, Bastndsite, 



Al 20-08 



Ca - 17-55 



Mg _ . trace 



K *12 



Na ._ -.- -32 



Cu -.-.- -17 



F -. 28-00 



H 2 14-24 



Quartz and oxygen .. _ 19-52 



100-00 



Neglecting copper, alkalies, and the oxygen calculated for 

 their oxides, and assuming the water to exist entirely as 

 hydroxyl, the following not very satisfactory atomic ratios 

 result : 



Al -7407 2 



Ca -4380 1*18 



F _ 1-4690 



Hydroxyl 1-5808 



which become 



Al -7407 2 



Ca -3712 1 



F 1-3354) . . 



Hydroxyl 1*5808 j ' ° ' 



if enough calcium and its equivalent in fluorine are subtracted 

 to make the ratio Al : Ca exactly 2 : 1, on the not improbable 

 assumption that fluorite is present as an admixture, an assump- 

 tion that had to be made also for the Colorado prosopite in 

 order to bring it into close agreement with Brandl's formula. 



There is now a deficiency in the acidic radicals. The 

 figures for Al, Ca, and H 2 are undoubtedly very nearly cor- 

 rect while the fluorine may well be half a per cent low, having 

 been determined by the Berzelian method, owing to the diffi- 

 culty of securing complete decomposition of the fine powder 

 by a single treatment with sulphuric acid. Let it be permitted 

 to balance the basic and acidic radicals by raising the fluorine, 

 and to figure the ideal percentages on this basis. These 

 become of interest when compared with the corresponding 

 figures for prosopite from Al ten berg and Pike's Peak as given 

 below : 



Altenberg. Pike's Peak. Utah. 



Al 23-37 22-02 22*74 



Ca 10-19 17-28 16-85 



F_. 35-01 33-18 29-95 



H 2 12-41 13-46 16-12 



O 1258 13-41 14-34 



100-00 



