but only questions of names. Within the field of names it should only comprehend what Stahl and the phlogistonists understand by them. It should therefore not attempt the classification of the elements, nor the classification of compounds made by combining elements. It should discuss no analysis unless the data be compiled from existing authorities. It should not regulate the nomenclature of somatology, for that belongs to physics and mechanics; it should not regulate the nomenclature of reactions, for that belongs to magic,-in fact, it should not meddle with names at all, for that is the domain of philology:"-would we ever have had a science of chemistry at all, or would Lavoisier and his colleagues have persisted in their reckless course of counselling and devising? In this connection the words of the great Berzelius are very applicable: "In every science a systematic nomenclature is necessary, but in none more than in chemistry. The confusion which reigned prior to the happy idea of Guyton de Morveau is a proof. The nomenclature which chemists have employed since 1780 is the fruit of his labors, sustained and directed by Lavoisier, Berthollet, and Fourcroy. The advantage that it presents is that whoever learns to recognize a compound can give it its true name without knowing it beforehand, so that it is unnecessary to charge the memory with a large number of different terms. Furthermore, scientific nomenclature is in itself the expression of a complete theory, so that if, on the one hand, the theory furnish the name, on the other the name indicates the theory. It has been objected to this relation of a nomenclature to theory that it obliges the names to be changed with the theories, which would not be necessary in the employment of purely technical terms, that are always preserved without alteration. But as these changes are ordinarily the results of progress in the direction of clearer notions, the change of nomenclature, far from injuring, is, on the contrary, another means for facilitating the march of ideas. In general, nothing which contributes towards rendering any part of a science stationary is advantageous: everything must advance equally in proportion to the multiplication of discoveries and knowledge." (Berzelius, "Treatise on Chemistry," vol. i., Introduction, 1829.) It is tolerably sure that if Mr. Gilbert expects the International Congress of Geologists to eschew all questions of science in its debates, and devote itself to the employment of playing at logograms exclusively with old data, he will be disappointed.Persifor Frazer. On the Homologies of Edestus.'-The genus Edestus was formed by Professor Leidy to comprise certain singular fossils from the coal-measures of the West, about which various theories have been held. The one generally received is that they are dorsal spines used as weapons of defence or offence. About a year and a half ago Dr. H. Woodward, of London, suggested that they might be pectoral fins similar to those of Pelecopterus, a genus described by Professor Cope from the Cretaceous of Kansas. The absence of any trace of articulation, the apparent evidence that there were ligaments extending to the base of Abstract of a paper read before the American Association for the Advancement of Science, August 15, 1887. the denticles, the segmented character of the fossils, and the fact that the segments are found singly, and of different sizes, which would indicate that they are shed like teeth, together with the presence of a slender curved basal bone (similar to that in Onychodus of the Devonian of Ohio) in the Australian form described by Dr. Woodward, led the author to think that these fossils are neither dorsal spines nor pectoral fins, but intermandibular teeth, which had a membranous or cartilaginous support in the American forms, and an osseous support in the Australian. These supports would bear the same relation to the mandibular arch that the glosso-hyal does to the hyoid arch.—Fanny R. M. Hitchcock. MINERALOGY AND PETROGRAPHY.' Petrographical News. In the continuation of his work on the rocks collected by the "Challenger" expedition, Renard has reached the discussion of the geology of the islands in the Indian Ocean. Those situated in the meridional part of the ocean are divided into five groups, three of which have been examined in detail. They are all of volcanic origin, and are in no way connected with Madagascar or the land within the Antarctic circle. The island Marion 3 is formed of volcanic rocks of two distinct ages, readily distinguishable by differences in the character of the vegetation they support. They both consist of feldspathic basalts, with anorthite as the plagioclastic constituent. The rocks of the island Heard are very similar to those of Marion. In the neighborhood of Corinthian Bay the prevailing rock is a feldspathic basalt, in which Baveno twins of bytownite are crowded together in groups. Many of these are optically anomalous in their action between crossed nicols, a fact supposed by Renard to be due to their fine lamellation. The olivine shows cleavages parallel to oP and a pinacoid. In some cases it has suffered alteration into pilite. In addition to the basalts a few specimens of limburgite were also collected.The same author has recently studied the rocks of Kerquellen Land, which had already been examined to some extent by J. Roth. Renard finds that these rocks consist principally of basalts, with amygdules of analcite and zeolites. The grains of olivine in them are grouped together like the chondra of meteoric stones. In addition to the basalts there occur on the island trachites, limburgite, and phonolites. Of these the trachytes and phonolites are older than the basalts. Two late articles on the petrography of the Tyrol add several interesting facts to our knowledge of this reEdited by Dr. W. S. BAYLEY, Madison, Wisconsin. 2 American Naturalist, Notes, 1886, p. 640. 3 Bull. d. 1. Soc. Roy. de Belg., 1886, iii. p. 245.. 4 Bul. du Mus. Roy. d'Hist. Nat. de Belg., iv. p. 223. 5 Monatsb. d. Kön. Akad. Berlin, 1875, p. 723. gion. Baron von Foullon separates the porphyrites of the Tyrol into quartz-porphyrites, quartz-mica-porphyrites, and diabaseporphyrites. In connection with the first group, Von Foullon records the replacement of hornblende by augite near the contact of the quartz-porphyrite and granite. The second group is characterized by the presence of garnet and an epidote, with the unusual pleochroism wine-yellow and violet. Intergrowths of this mineral and hornblende take place in such a manner that the axes ɓ and c' of the former are parallel with c' and ɓ of the latter. The hornblende in the rock often shows a parting parallel to op. In the Neues Jahrbuch Cathrein describes six rocks from various localities in the Alps. A staurolite-mica-schist occurs at Oberinnthal. It contains numerous hemimorphic crystals of tourmaline. A garnet amphibolite is remarkable for the occurrence in it of plagioclase pseudomorphs of garnet. The interior of the garnets are changed into plagioclase, around which is an exterior zone of compact hornblende. The serpentine of this region is an altered pyroxene rock. The remains of bronzite, enstatite, and diallage can still be detected in it. The most instructive portion of the paper is that devoted to the porphyrites and pitchstone-porphyries. Of the former several varieties are recognized. The first contains epidotized plagioclase and crystals of compact hornblende. In the second, in which uralite and a little augite occur instead of hornblende, the plagioclase is sausuritized. A third variety contains brown garnets in oscillatory combinations of the dodecahedron and the icositetrahedron. They are the oldest constituent. Of the pitchstone-porphyry the author says, this rock occurs in large independent masses, breaking through the prevailing quartz-porphyry in large dikes and bosses, no transition between the two being anywhere discernible.—A schistose rock from the Grossarlthal in the Alps contains chloritoid instead of mica as its bisilicate constituent. Cathrein 3 calls it a chloritoid schist. It contains nearly five per cent. of rutile and sphene.- -The rocks of the Hereroland in Southwest Africa belong principally to the class of the older eruptives. The quartz grains of some of the granites contain fluid inclusions with hexahedral crystals, and are pierced through by little needles of sillimanite. The most interesting observations are those on the crystalline schists. The gneiss is remarkable for the unusual association and decomposition of its constituents. The biotite is intergrown with sillimanite, and contains zircon crystals surrounded by pleochroic "höfe." Orthoclase and microcline are intergrown in the manner described by Becke. The former has I Jahrb. d. k. k. geol. Reichsaust, 1886, p. 747. 2 Neues Jahrb. f. Min., etc., 1887, i. p. 147. 3 Min. u. Petrog. Mitth., viii., 1887, p. 331. 5 Cf. Min. u. Petrog. Mitth., iv., Taf. ii. Fig. 8. undergone alteration into pseudophite, yielding a product having very much the appearance of serpentinized olivine. The augite gneisses are divided into scapolite-bearing varieties and those that contain wallastonite. The cleavage in the scapolite, as observed by Wulf, is parallel to P, and is not parallel to ∞ P∞, as given in the text-books. The latter is probably a parting. The composition of the augite in both varieties approaches that of diopside. Other rocks described by Wulf are diorites, basalts, amphibolites, diorite-schists, mica-schists, etc.-Lacroix describes a gabbro from St. Clement in the Puy-de-Dôme, which contains, in addition to the usual constituents, the minerals vesuvianite, sphene, and wallastonite. The feldspar is anorthite with only 0.53 per cent. of Na2O. It presents the appearance of having been crushed and recemented, the cementing material possessing the same optical orientation as the pieces it surrounds. Mineralogical News.-Within the past few months the properties of quite a number of rare minerals have been investigated by mineralogists in this country and in Europe, with the results indicated below. W. C. Brögger' describes in detail the characteristics of låvenite and cappelinite. The former occurs on the island Låven in Langesundsfjord, and is also found in the eleolite syenite of the Province of Rio Janeiro, Brazil. It forms brown to yellow, slightly transparent crystals, with a prismatic habit and vitreous lustre. It is monoclinic in crystallization with à: 5: c' 1.0811: 1:0.8133, P=71° 24%. The twinning and the cleavage planes are parallel to the orthopinacoid, while the plane of the optical axes is the clinopinacoid. The mineral is strongly pleochroic, ĉ>b> a = red-brown, yellowish-green, and wine-yellow. Its specific gravity is 3.51, and its composition: MnO CaO Na2O 5.06 SiO2 ZrO2 Fe2Og (?) 5.64 I 1.00 11.32 Loss at red heat 1.03 33.71 31.65 Cappelinite is found in a small vein in the augite syenite of Little Arō in Langesundsfjord. It occurs in thick brown hexagonal prismatic crystals with a fatty lustre. Their axial ration is I: 0.4301. Their analysis yielded: SiO, B2O, Y2O, La(Di),0, Ce,O, ThO, Bao Cao Na,O KO H2O 14.16 17.13 52.55 2.97 1.23 0.79 8.15 0.61 0.39 0.21 1.81 Warwickite, the borotitanate of magnesium and iron, occurring at Edenville, N. Y., is generally found in prismatic crystals elongated in the direction of the vertical axis, with a cleavage parallel to the clinopinacoid. Lacroix3 has succeeded in obtaining measurements of these, which indicate a symmetry corresponding to that of the rhombic system. In accordance with I Zeitsch. f. Kryst., x., 1885, p. 503, and Geol. För. i. Stockh. Förh., Bd. vii. p. 598. 2 Fr. Graeff, N. J. B., 1887, i. p. 201. 3 Bul. d. 1. Soc. Fr. du Min., ix. p. 74. 6 this view the plane of their optical axes is the orthopinacoid. Their bisectrix is positive and perpendicular to P. 2 E=125°. The mineral is pleochroic in red and brown tints. Withamite from the porphyrites of Glencoe, County Argyle, Scotland, the same author regards' simply as epidote. He also thinks that mismondine, sasonite, ottrelite, venasquite, and phyllite are merely varieties of chloritoid, the optical properties of which he describes at length. Xantholite he supposed to be identical with staurolite.-J. Strüver does not consider gastaldite as a variety of glaucophane, but regards both minerals as distinct members of the amphibole group. According to Lacroix 5 the kirwanite (of Thomson) is a mixture of amphibole, secondary quartz, and epidote. The same author finds that hullite from Belfast is not homogeneous, and therefore should not be regarded as a definite mineral species. He states also that Dufrenoy's dréelite is an impure barite.-New analyses of agalmatolite indicate that most of the substance to which this name has been given really possesses no definite composition, but is probably a mixture of silica and hydrated silicates of potassium and aluminium, resulting from the decomposition of orthoclase. An apparently regular mineral has been found by Vom Rath in the druses of an andesite near the apex of Cerro S. Cristobal near Pachuca, Mexico. It occurs in small octahedra, sometimes twinned according to the spinel law. It is often intergrown with tridymite. Hardness = 6-7. Specific gravity 2.27. Its composition is SiO, 91 per cent. Fe2O3.Al2O3 = 6.2 per cent. Both Vom Rath and Bauer regard it as most probably regularly crystallizing silica. It has been called christobalite to distinguish it from quartz, tridymite, vestan (Jensch, Pog. Ann., 1858, p. 320), and asmanite.A new variety of dufrenite has been observed by Messrs. Kinch, Butler, and Miers in Cornwall, England. When fresh it is found in small black or apple-green orthorhombic plates, which in the thin section appear yellow or brown. Its hardness is 4.5 and specific gravity 3.233. An analysis yielded: = = Fe2O3 55.93 8 CaO 1.51 The composition of the mineral corresponds with that of Streng's kraurite.10. -The composition of a micaceous mineral from a limestone in the Kaiserstuhl is recorded by Knop" as follows: 6 Ib., p. 435. 7 Min. Mag., July, 1886, pp. 24 and 29; Dec. 1886, p. 74. 8 Neues Jahrb. f. Min., etc., 1887, i. p. 198. 9 Min. Mag., Dec. 1886, p. 65. 10 Neues Jahrb. f. Min., 1881, i. p. 101. "Zeits. f. Kryst., xii. p. 607. |