304 W. P. Ileadden — Some Phosphorescent Calcites. 



the calcites themselves, for they were subsequently insolated 

 and phosphoresced brightly. 



I have stated that ignition destroys the property of becom- 

 ing phosphorescent by insolation, so does solution ; neither the 

 solution itself nor the carbonates recovered from it by frac- 

 tional precipitation show this property. 



A yellow color in the Joplin calcite seems to be a sure indi- 

 cation that the sample will become phosphorescent upon 

 insolation. Two things suggested themselves as possible expla- 

 nations of these properties, the presence of sulphides and of 

 organic matter, but I was unable to detect the presence of 

 either of these. It, however, still seemed probable to me that 

 this property was due to the chemical composition of the yel- 

 low portion : with this idea in view I submitted a carefully 

 selected portion of the yellow calcite to analysis. This analy- 

 sis gave but little promise that I might succeed by pursuing 

 this method of investigation, as the percentages obtained for 

 the calcic oxide and carbonic acid were almost exactly those 

 required by theory. The precipitate, usually composed of 

 ferric and aluminic oxide, amounted to less than O10 per cent, 

 but it was the deportment of this precipitate that led me to 

 repeat the analysis. The small amount missing in my first 

 analysis, an amount less than 0*20 per cent, proved to be the 

 interesting part of the mineral, whose analysis finally presented 

 the following results : 



Analyses of Yellow Calcite from Joplin, Mo. 



Si0 2 0-032 



C0 2 43-950* 



S0 3 trace 



H 2 S ._ none 



P O trace 



2 5 



CI trace 



CaO 55-740 



SrO .... trace 



MgO 0-113 



MnO 0-045 



FeQ _ _ - . 0-046 



ZnO . 0-014 



A1 2 3 -. trace 



O 2 3 - . . trace 



Ce 2 3 .. 0-007 



Di 2 0„ Sra 2 3 . La 2 3 0-012 



Yt 2 3 .Er 2 3 0-013 



NH 5 trace 



Na 2 trace 



Total 99-975 



* One hundred grams of selected material gave 10 cc of gas not absorbed 

 by KOH solution. 



