MORSE. — STUDIES ON FLDORITE. 603 



final answer having been reached. Two diametrically opposite opinions 

 still exist, — one, that the color of many minerals, fluorite among them, 

 is due wholly to the presence of organic coloring materials, 25 the other, 

 that there is no sufficient proof for this opinion. 20 The method of study 

 in all of these researches was the one which suggests itself immediately, 

 — heating the mineral until the organic substances present are driven off 

 or decomposed, and collecting the gases and the liquid distillate when 

 any are produced. 



"Wyrouboff 27 was the first to make a categorical statement in the 

 matter. He heated minerals in a current of oxygen and determined 

 the resulting carbon dioxide and water, finding from his experiments 

 that the amount of carbon and hydrogen found in the analyses was 

 nearly proportional to the intensity of the color of the mineral. These 

 experiments were especially on fluorspars from different localities and 

 of different colors, and his decision was that the colors were organic. 

 Foerster 28 repeated these experiments on a number of fluorites and 

 showed that the quantities of hydrogen and carbon produced are not by 

 any means proportional to the intensity of color in the mineral, clear 

 white specimens often showing as large an amount of organic impurity 

 as the most deeply colored. My own analyses confirm these results of 

 Foerster's in every way, but it does not by any means follow from these 

 results that the coloring substances are not organic. The only conclu- 

 sion which seems to me justified is that the other crystals contain organic 

 substances which are not colored. At a much later date Wein- 

 schenck 29 made an exhaustive series of analyses to determine the 

 same question, arriving at the conclusion opposite to that of Wyrouboff, 

 and a little later Kraatz and Wohler 30 arrived at the opposite 

 result from an equally careful series of analyses. The question as to 

 the cause of the color of fluorspar still remains in this unsettled state. 



The Odor of Fluorspar. 



Another peculiarity of fluorspar from many sources, and one which 

 might perhaps be expected to throw some light on the source of its 



25 Wyrouboff, Bull. Soc. Chim., 1866, 334 ; Kraatz and Wohler, see Ztsch. fur 

 Min. u. Cryst., 33, 632 (1900). 



26 Weinsclienck, Ztsch. anorg. Chem., 12, 375 (1896) ; Foerster, Pogg. Ann., 

 143, 173 (1879). 



« Bull. Soc. Chim., 1866, 334. 28 Pogg. Ann., 143, 173 (1879). 



29 Ztsch. anorg. Chem., 12, 375 (1896). 



30 See Ztsch. fur Min. u. Cryst., 33, 632 (1900). 



