a 
770 The American Naturalist. [September, 
particles are intermingled indiscriminately with those that are biaxial. 
On the contact with the veins fine masses of tremolite have been 
developed in the limestone. The quartz crystals of Suttrop, Vlotho 
and Bramsche in Westphalia, and incidentally crystals from other 
localities, have been thoroughly studied by Bomer,” especially with 
reference to their etched figures and electrical properties. The Westpha- 
lian crystals were treated with hydrofluoric acid, and sections cut from 
them parallel to oP were subjected to the action of the same reagent. 
The sections were also examined for circular polarization, and the entire 
crystals for electrical manifestations. The Vlotho and Bramsch crys- 
tals, the former of which occur in druses on marl and the latter 
implanted in white vein quartz in quartzite, are quite simple, while 
the Suttrop crystals, found loose in the soil overlying a quartzite com- 
posed almost exclusively of quartz crystals, are very complicated in 
structure. These consist usually of two or more individuals twinned, 
and often intergrown with others in the parallel position. The forms of 
the etched figures produced on oP vary widely. They depend upon the 
strength of acid used and upon the temperature at which the action 
takes place. With increasing strength of acid the figures suffer a 
rotation around the vertical axes of the crystals, and in the direction 
of its polarization, i. e. in right polarizing crystals, the rotation is to 
the right and in left-handed crystals to the left. Many other interest- 
ing results in connection with the etched figures of quartz were obtained 
by the author and some of them contradict the results of other inves- 
tigators. With reference to the pyro-electrical properties of the erys- 
tals it was found that in small ones the negative and positive areas 
were irregularly distributed, while in large ones the distribution was 
more regular. Both large and small crystals act similarly when cooled 
in ether or in water. In each case the trapezohedral edges are posi- 
tive. 
Mineralogical News.—Among the wonderful pseudomorphs of 
serpentine from the Tilly Foster Mine, N. Y., Dana mentioned a cubic 
substance whose predecessor was unknown. Friedel has reexamined 
this substance, and has found in it a central cone of amorphous serpen- 
tine, surrounded by a fibrous envelope of the same mineral. The 
arrangement of the fibres is so regular that the author concludes that 
the cubic form is due entirely to it, and that’ there is no reason for 
- supposing the form to be pseudomorphic.——Excellent specimens of 
“Neues Jahrb. f. Min., ete., B. B., vii, p. 516. 
18Bull, Soc. Franç. d. Min., xiv. p. 120. 
