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with 3.01 per cent Mo,Os, and in another case with 1.91 per cent Cr,O, was prepared, but similar experiments with the oxides of nickel and cobalt were not successful, the rutile crystals containing no appreciable trace of Ni or Co. Chromiferous crystals of cassiterite were also formed. It seems, therefore, that these substances have a peculiar affinity for the oxides of the type R,0g, but not for those of the form RO.

Colored specimens of all three minerals become permanently lighter in color on heating.

Marignac's process for fusing zircon (i.e., with KF or with KF HF) was tried with rutile and cassiterite. Like zircon they both fuse rather readily, forming K, TiF. and K, SnF, respectively.

Miscellaneous Notes.-Wülfingo describes a simple apparatus for obtaining monochromatic light from direct sunlight. The experiments on quartz seem to show that the apparatus works with a good degree of accuracy. Measurements of the index of refraction of diamond

gave for A, n=2.4024 ; for D, n=2.4175; and for H, n=2.4652. These are three of several values determined. The specific gravity of these diamonds referred to water at 4° was found to be 2.5223.003. Hematite from Elba was also investigated, giving:

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The specific gravity at 4° is 5.285.002. A description is also given of a spectrum apparatus for use with a microscope or an axial angle instrument. In a later note Wülfing gives a table comparing the values of the indices of refraction of the diamond obtained by himself with those determined by Walter ; the agreement is very close. He states that either apparatus above mentioned may be obtained of Eug. Albrecht in Tübingen.

Kretschmer' describes the occurrence of garnet, vesuvianite, wollastonite, epidote, augite, quartz and calcite at the contact of marble with granite near Friedeberg in Silesia. Minute details as to locality, association and crystal form are recorded.

Goguel® reports on the crystal form, and in some cases on the optical behavior of formopyrine, C12 H, N, O, and its addition salts with

5 Tscherm. Mitth., XV, pp. 47–76, 1895. 6 Ibid, p. 350. * Tscherm. Mitth., XV, pp. 9–28, 1895. 8 Bull. Soc. Fr. Min., XVIII, pp. 27-31, 1895.

hydrochloric, sulphuric, nitric, phosphoric and oxalic acids.—Duparc and Pearce have measured the crystal angles and observed the optical properties of eight new chemical compounds. These are benzoyl malic acid, sodium orthophenyl-benzoate, Potassium orthophenyl-benzoate, ammonium phenyl-glycolate, dextrocinchonine phenyl-glycolate, benzylic ether of bromo-tolu-quinone oxime, potassium luteo-phosphomolybdate and a potassium luteo-phosphotungstate.

Of late numerous additions have been made to our knowledge of the crystallographic and optical constants of organic compounds. The following three papers in Volume XXV in the Zeitschrift für KrystalJographie may be cited as important contributions to this line. 1. The Crystal form of Some New Halogen Derivatives of Camphor, by F. S. Kipping and W. J. Pope; 2. On the Crystal Form of Some Organic Compounds, by W. J. Pope; 3. Crystallographic and Optical Investigations on Some Organic Compounds, by E. A. Wülfing.

An artificial cassiterite investigated by Arzruni" shows distinct dichroism with the ray vibrating parallel to the vertical axis colorless, while the ray vibrating at right angles thereto is pink. The crystals reach a half centimeter in thickness and twice that in length. Twins, which are so common with natural cassiterite, were not observed. The angles measured coincide within 2' with those given by Becke for the natural mineral. The mean values from two determinations of the indices of refraction are : Li Na

TI 1.9816 1.9968

2.0093 2.0817 2.0929

2.1053 These numbers agree as well as could be expected with those obtained by Grubenmann for cassiterite, showing that the natural and artificial products are practically identical.

Schmidt" gives at great length tables showing the recurrence of like interfacial angles in the regular system. As an extreme example, the angle 35° 15' 52" occurs between eleven pairs of faces, the cube, octahedron or dodecahedron constituting one face of each pair. The table at the end of the paper may be of use for rapidly identifying rare faces on regular crystals.

Sohncke? shows that in accordance with his views of crystal structure no circular polarization is to be expected in crystals of the pyramidal

9 Bull. Soc. Fr. Min., XVIII, pp. 31--43, 1895. 10 Zeitschr. f. Kryst., XXV, pp. 467--470, 1895. " Zeitschr. f. Kryst., XXV, pp. 477--503, 1895. 12 Zeitschr. f. Kryst., XXV, p. 529, 1895.

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tetragonal class (hemimorphic hemihedral division of the tetragonal
system). So far as known, circular polarization is not exhibited by
crystals with this grade of symmetry.

PETROGRAPHY.
Petrography of the Bearpaw Mountains, Montana. The
Bearpaw Mountains are the dissected remains of a group of Tertiary
volcanoes. Their cores of the old volcanoes are granular rocks, their
lavas and tuffs are represented by basic sheets and beds. The lavas
are largely basalts, leucite-basalt and other similar basic types.?

The cores consist of mica-trachytes, quartz-syenite, porphyries, con-
taining aegerite-augite and anothoclase-phenocrysts, in which are im-
bedded microlites of oligoclase, trachytes containing hornblende and
diopside and shonkinite. A few miles from Bearpaw Peak a denuded
core is exposed, which furnishes a good example of the differentiation
of a syenite in place. The intrusion is laccolitic in character. Around
its borders it has highly altered the sedimentary rocks with which it is
in contact. The most acid portion of the laccolite is a light aplitic
syenite containing quartz and diopside. The main mass is a more basic
syenite resembling monzonite or yogoite. It contains diopside and
much plagioclase. The most basic phase is a shonkinite. Analyses
for the three principal types follow :

SiO, A1,0, Fe,O, FeO MgO CaO Na,0 K,0 H,O, Other Total Quartz-syenite 68.34 15.32 1.90 .84 .54 .92 5.45 5.62.45 .57

= 99.95 Monzopite 52.81 15.66 3.06 4.76 4.99 7.57 3.60 4.84 1.09 1.86 =100.24 Shonkinite 50.00 9.87 3.46 5.01 11.92 8.31 2.41 5.02 1.33 2.68 =100.01

The totals corrected for Fe and Ce are 99.94, 100.22 and 99.93 respec-
tively.

Two French Rocks. In the serpentine of St. Préjet-Armadon,
Haute-Loire, France, Lacrou' finds nodules composed of asbestiform
gedrite surrounding a kernel of serpentine or biotite. The nodules are
separated from the serpentine by an envelope of biotite. They are sup-

Edited by Dr. W. S. Bayley, Colby University, Waterville, Me.
2 Weed and Pirson : Amer. Journ. Sci., IV, Vol. 1, p. 283 and 351.
Bull, Soc. Franc. d. Min., XIX, p. 687.

posed to be of secondary origin. 'Bronzite and asbestus both occur in the rock. In the norite area of Arvien, Auvergne, the same author describes a variety of this rock which is characterized by the presence of secondary reaction, rims of anthophyllite and actinolite between its hypersthene and plagioclase, the former appearing next to the pyroxene. The plagioclase of the rock is often altered to actinolite, garnet and albite, while the hypersthene is changed to an aggregate of anthophyllite.

The Granite of the Himalayas.-McMahon describes the granite of the N. A. Himalayas. Although highly foliated in the borders of its masses, the rock is shown to be eruptive. The author thinks the foliation is due to pressure upon the rock before it finally solidified. He attempted to show that this schistosity could not possibly have been produced after the rock cooled. The granite is coarsely porphyritic with large orthoclase crystals in a medium to fine grained groundmass composed of the usual constituents of granite. This is cut by tiny veins of quartz which are supposed to represent the micrystallized residue left after the first partial consolidation of the rock, or to be the result of a partial fusion of the quartz grains originally occurring in it. This quartz, though it presents the usual aspects of secondary quartz, is thought to have been injected into the vein spaces while it was in a molten condition. Sinuous areas and viens of microcrystalline mica are likewise observed in the granite, and these are thought to have been produced by the rapid crystallization of mica that had been melted, and not by the crushing and shearing of the original micas nor by secondary processes of any other kind. The paper is well illustrated by photo-micrographs.

California Rocks.-Fairbanks' describes the rocks of Eastern California between Mono Lake and the Mojave desert as comprising both sedimentary and igneous forms. Among the latter are both granitic and volcanic varieties. The granites form the eastern slope of the Sierra Nevadas. In the northern portion of the area it is a coarsely porphyritic biotite hornblende variety. In the southern portion it is replaced by a more basic phase containing less hornblende. The volcanic rocks met with in the district are andesitic flows, dykes and tuffs, and basalt flows among the more recent rocks and liparites among

the more ancient ones. The microscopical description of the type is deferred to a later paper.

* Proc. Geologists Association, Vol. XIV, p. 287. 6 Amer. Geologist, Vol XVII, p. 63.

Turner gives a classification of the igneous rocks studied by himself from various places in California. He divides them into families in accordance with their mineralogical composition, including in the same family all those rocks with the same composition irrespective of structure. He then takes up the syenites and discusses them in some detail. The family is made to include syenites (granular), syenite-porphyries (porphyritic) and trachytes (microlitic and glassy) and apotrachytes. The syenites include soda-syenite or albitite, augite-syenite, hornblende-syenite and mica-syenite. The apo-trachytes include among other rocks Rosenbusch's orthophyres and keratophyres. Until very recently no rocks of the syenite family have been proven to occur within the borders of the State. All those rocks described as such are now known to be hornblende-andesites, granites or diorites. The author refers briefly to the known occurrence of the syenites in the State and describes more fully some new ones.

He reports dykes of white albitite-porphyries or soda-syenite porphyries in the rocks of the Mother lode quartz mines. In the bed of Moccasin Creek the rock consists of quartz, muscovite and albite, but in other places it consists almost exclusively of albite with a few grains of an olivine-green mineral thought to be aegerite. The rock resembles somewhat Brögger's solos bergite and Palache's albite rock containing crossite. An analysis of one specimen gave:

Sio, TiO, AI,O, Fe,0, FeO Cao MgO K,O Na, H,0 P,OTotal 67.53 .07 18.57 1.13 .08.55 .24 .10 · 11.50 .46 .11 =100.34

Gabbro-Gneiss from Russell. The gabbro of Russell, St. Lawrence Co., N. Y., is said by Smyth' to change its character rapidly in consequence of a variation in grain from moderately fine to very coarse, in structure from porphyritic to granular and in color from black to gray. Upon alteration the gabbro passes into a rock made up of red masses in a groundmass of gabbro. In other places it becomes schistose, when it takes on a granulitic texture. Sometimes hornblende is developed in it in long narrow plates that run approximately at right angles to the schistosity, causing the rock to resemble a metamorphosed sediment. Even in the most gabbroitic varieties of the rock the plagioclase is changed into an aggregate of secondary products, among which scapolite is the most common. In the change of the massive gabbro into the schistose variety the constituents are first

6 Ib., Vol. XVII, p. 375. Amer. Jour. Sci., Vol. 1, p. 273.

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