PETBOLOGY. 215 



■ 



Among the quartzless i)orphyries, distinguishes those with orthoclaso 

 and albite, e. g. the micaceous porphyry of Oehrenstock, and those with 

 a felspar differing in composition from oligoclase, and called paroligo- 

 clase. E. B. T, 



Selwyn, R. A. C. Not^js on a stratigraphical collection of Canadian 

 rocks. [Appended to Descriptive Catalogue of a Collection of 

 Minerals exhibited in. the Philadelphia Exhibition, pp. 137-147.] 

 Montreal. 8vo. 

 Notes accompanying a collection of 902 specimens of rocks and 172 

 fossils, arranged stratigraphically to illustrate the geology of Canada. 

 The collection of "Economic Minerals" also contains many rock-speci- 

 mens, such as coals, building-stones, clays, &c. E. W. li. 



Senft, Dr. Ferd. Eels- und Erdboden, Lehre von der Enstehung-Hnd 

 Natur dcs Erdbodens. [Kocks and Soils.] Pp. xvi, 392; IT cuts. 

 8vo. Munich. 



Begins the consideration of the rocks of the earth's crust by de- 

 scribing the minerals of which they are formed, under the head of salts, 

 spars, metallic oxides, &c., pp. 12-81. Silicates are grouped under 

 those containing clay (felspars, zeolites, &c.), or those with magnesia 

 (hornblende, augite, mica), pp. 84-137. By an aggregation of these 

 are formed the mixed crystalline rocks, thus divided : — Those rich in (1) 

 felspar, (2) mica, (3) hornblende, (4) augite, pp. 137-147. Sedimentary 

 or klastic rocks, pp. 147-160. The process of weathering and detrition 

 by which soil is formed are fully treated ; the formation of humus, its 

 chemical action, and the exigencies of plant-life and its dependence on 

 the nature of the soil, form the practical side of the question, up to which 

 the petrological portion leads. E. B. T. 



Sjbgren, A, Om platinans formodade modcrklyft. [The supposed 



Matrix-rock of Platinum.] Geol. Fdren. StocJcJiohn Fork. Bd. iii. 



pp. 179-181. 



Concludes, from microscopical researches, that the three metals, 



chromium, vanadium, and platinum, have a similar origin, and that 



they were originally formed in a matrix of eruptive rock rich in olivine. 



The rocks investigated are : — Serpentine, with platinum, from Auro- 



rinsky, Martianfluss, V. of Ural ; platinum-conglomerate from Siberia ; 



Chromo-ore from Frankenstein Grochau, and from Veltjord in Norway. 



E. E. 

 Stagi, Dr. Francesco. Ricerche Chimichc sui Calcari doi Monti 

 Pisani. [Chemical Examination of Limestones of Pisa.] Atti 

 Soc. Tosc. Sci. Nat. vol. ii. pp. 08. 

 Describes many limestones, giving analyses. 



Steenstrup, K. J. V. Om de Nordenskioldske Ja^rnmasser, og om 

 Forekomsten af gedigcnt Ja?rii i Basalt. [Nordcnskiold's Iron 

 Blocks, and the Occurrence of Native Iron in Basalt.] Vid. Nat, 

 Foren, Kjobenhavn, 1875, pp. 284-306, 2 plates. 



