June 29, 1883.] 



SCIENCE. 



609 



Brogger on the schists of Norway. Both found fos- 

 sils in crystalline marble, in mica schist, and in other 

 rocks of like metamorphic character. The latter 

 even found the remains of Orthis enclosed in dodeca- 

 hedral garnet. Likewise the Carrara marble of Italy 

 has been shown to overlie and underlie fossiliferous 

 strata. From these observations, there seems to be 

 no doubt that the general belief that schists are 

 metamorphosed sedimentary rocks is substantiated, 

 sa far as these regions are concerned ; and they afford 

 no aid to the revived and remodelled Wernerian hy- 

 pothesis that has been made so prominent in this 

 country during recent years. Without objecting to 

 the work of the writers above referred to, attention 

 may be called to the tendency in most observers, 

 when they have proved the origin of a rock, to as- 

 sume that all associated rocks are the same, leading 

 one class to hold to the eruptive origin of all the 

 rocks seen, and another to their sedimentary origin. 

 In regions of crystalline rocks, both classes of rocks 

 would naturally be expected to occur together, and it 

 would be well if the utmost care should be used to 

 - prove the origin of every rock in the district studied. 

 — (Bull. mus. roy. Belr/., i. ; Die silur. etagen 2 m. 3 ; 

 Silurfoss. or/ konyl. i Berrjensk. ; Nature, xxvi. 567, 

 xxvii. 121.) M. E. w. [1152 



Carboniferous gneiss and schist. — Some 

 gneisses and scliists, which, from the associated plant- 

 remains, are referred to the carboniferous, liave been 

 microscopically studied by Foullon. They are asso- 

 ciated with the graphite deposits about Kaisereberg 

 in Steiermark. The gneiss is composed of felspar 

 (albite) quartz, rauscovite, and chlorite, with a little 

 epidote, biotite, and, in one case, tourmaline. Tlie 

 phyllite gneiss is fine-grained, and composed of 

 quartz, orthoclase (microcline), and tourmaline ; 

 while the graphitic schist is also a purely crystalline 

 mass of quartz and chloritoid, excepting some por- 

 tions in which are found plant-impressions and plates 

 of a micaceous mineral. Zircon and an asbestiform 

 mineral were also seen. — {Verh. geol. relclisanxt., 

 Jan., 1S83.) m. e. w. [1153 



MINERALOGY. 



Some results of the alteration of minerals. 

 — The following facts are communicated by F. A. 

 Genth : — 



Albite from orthoclase. — This interesting altera- 

 tion is well exhibited at the gneiss-quarries of upper 

 Avondale, Penn., where flesh-colored orthoclase is 

 found much decomposed, the cavities being filled with 

 albite associated with muscovite. 



Anthophyllite from talc. — At Castle Rock, Dela- 

 ware county, Penn., talc occurs as the result of the 

 alteration of olivine, but in some cases this alteration 

 has proceeded farther. Radiating from a nucleus 

 of talc is a white or grayish mineral, with silky lustre 

 and prismatic cleavage at an obtuse angle, which 

 proved, upon analysis, to be anthophyllite. 



Talc pseudnmorph after magnetite. — In Hartford 

 county, Md., small octahedrons of scaly talc occur, 

 the scales being parallel to the ocfaheflval faces; and 

 sometimes the crystals contain in the interior a small 

 nucleus of magnetite. The author regards the crystals 

 as pseudomorphs after magnetite, and suggests that 

 a whole bed of steatite twelve to fifteen feet in thick- 

 ness, occurring at the above-mentioned place, may 

 have resulted from a like change from magnetite. — 

 {Proc. Amer. pldl. soc, xx. 392.) s. L. P. [1154 



■Wulf enite. — It has generally been accepted that 

 the red varieties of wulfenite found at many localities 



are colored by chromate of lead (PbCrOj), which is 

 isomorphOLis with the wulfenite PbMoOj. If this Is 

 true, lead chromate must be tetragonal in its crystalli- 

 zation, and triraorphic; for the natural variety, cro- 

 coite, is monoclinic, and again it is undoubtedly 

 orthorhombic, isomorphous with anglesite {PbS04). 

 In red crystals from Phoenixville, Penn., J. Lawrence 

 Smitli found vanadium and only a trace of chromium, 

 while Woliler detected vanadium in a variety from 

 Bleiberg in Carinthia. Owing to the dissimilarity 

 between molybdic and vanadic acids, it is not proba- 

 ble that any isomorphism exists between them, while 

 chromate and molybdate of lead, from a chemical 

 stand-point, can well be regarded as isomorphous. 

 To decide as to the true nature of the coloring-matter, 

 P. Grothhad various wulfenites examined by F. Jost, 

 with the following results. In a highly colored, yel- 

 lowish-red variety from Bleiberg, neither chromium 

 nor vanadium could be detected. In the red crystals 

 from Phoenixville, Penn., chromium was found, but 

 no trace of vanadium. The analysis gave 



PbO(60) + Mo03(39.21) + CrOjCO.SS) =99.59. 



The green pyromorphite accompanying wulfenite 

 from the latter locality contained no vanadium, but a 

 trace of chromium; while chromium was also found 

 in a yellowish-red pyromorphite from Leadhills, 

 Scotland. Here, certainly, no isomorphism can 

 exist between the chromate and phosphate of lead; 

 and the red color in the latter case must be due 

 either to the mechanical admixture of some chromate 

 or some pigment entirely independent of the chro- 

 mium. The fact that wulfenites, entirely free from 

 and containing a trace of chromium, occur of a red 

 color, makes it probable that the color is due to some 

 pigment, perhaps of organic origin, while the chro- 

 mate is present as a mechanical admixture, and in no 

 way related to the red color. — {Zeitsclir. kryst., vii. 

 592.) s. L. p. [1155 



METEOROLOGY. 



Solar physics. — A recent report on this subject 

 to the British government mentions India as a sat- 

 isfactory field in which to prosecute investigations 

 of solar radiation, and its connection with terrestrial 

 phenomena; calls attention to the importance of a 

 more satisfactory means of measuring directly the 

 sun's heat, tlie great obstacles presented in the 

 attempt to measure this heat at sea-level stations, 

 owing to the very great fluctuations in the observed 

 direct heat, even on clear days, due to invisible 

 vapor; and refers to the expedition of Prof. Lang- 

 ley to Mount Whitney, and the permanent establish- 

 ment of instruments at Leh in India, at an elevation 

 of 11,000 feet, in order to overcome these obstacles if 

 possible. A very useful, detailed catalogue of sun- 

 spot observations, and photographs of the sun, from 

 1832 to 1877, is given. A discussion of the influence 

 of the state of the sun upon the earth's temperature 

 is entered upon, in which an effort is made to con- 

 nect the range of temperature at the single station 

 Toronto, Canada, with the sun's spots. The results 

 arrived at seem to show that a maximum tempera- 

 ture range corresponds to a maximum number of 

 spots, and that the Toronto phases of temperature 

 range lag behind similar phases in solar spottedness 

 between one and two days. The first of these con- 

 clusions differs from the opinions held by some, and, 

 on taking the mean annual ranges, seems hardly sus- 

 tained. 



The following table gives the mean annual range 

 of temperature from 1841 to 1880, and mean annual 

 cloudiness from 18.53 to 1880, at Toronto, Canada. 

 Solar spot numbers are added for comparison. 



