530 General Notes. 
has been detected by Hintze? on a crystal of sphalerite from 
Striegau. ; 
MIscELLANEOUS.—As the result of a series of experiments upon 
the strongly pleochroic epidote of Sulzbachthal, Ramsay ? finds that 
the absorption colors of this mineral are not symmetrically arranged 
around the axes of elasticity vi and e lying in the plane of sym- 
metry. Moreover, he finds that the absorption axes—the direc- 
tions in which the greatest, the least and the mean absorption 
takes place—do not correspond with the axes of greatest, least and 
mean elasticity, as had already been indicated by earlier observa- 
tions. The direction of greatest absorption for the red ray in the 
clinopinacoid is inclined 28° to the axis of least elasticity, while 
‘concludes (1) that one of the absorption axes in monoclinic erys- 
tals coincides with the axis of symmetry b, while the other two 
lying in the plane of symmetry do not necessarily coincide with 
the axes of elasticity for the same color. In triclinic minerals 
there is no accordance between the absorption axes and the axes 
of elasticity. (2) The axes of greatest and of least absorption for 
any given color in triclinic minerals and the absorption axes lying 
in the plane of symmetry of monoclinic minerals are not always 
perpendicular to each other, as are the axes of elasticity.—The 
same subject is discussed mathematically by Drude,’ who calcu- 
lates the positions of absorption maxima in monoclinic and tri- 
clinic minerals from data obtained by Ramsay. He finds slight 
discordances between the observations of Ramsay and the theo- 
retical demands, but concludes that, on the whole, Voight’s* the- 
ory of absorption is substantiated—By supplying a blast lamp 
with warm air and with oxygen, Specia® has sticceeded in fusing 
many of the minerals infusible under ordinary conditions. The 
differences in their conduct under these changed conditions may 
glass when oxygen is used. Colorless topaz is difficultly fusibl 
in the first case, while it fuses readily with intumescence in the sec- 
ond case. Colorless zircon is infusible in both cases, but ponpon 
cloudy at the high temperature produced by the combustion wit) 
oxygen. 
1 Zeits. f. Kryst., xiii., 1887, p. 161. ; 
2 Zeits. f. Krystallographie, 1887, xiii., p. 98. 
3 Zeits. f. ITIN be Bie po ge xiii., p. 567. 
* Wiedem. A en., 1884 p- 577. ; 
s Atti. d. R. Accad. d. Scienze di Torino, xxii., p. 1887. Ref. N.J- B. 
1888, i., p. 177. 
