BihUographical Notices. 379 



of minerals ; tests with water and acids, and examination with the 

 blowpipe ; pleochroism is also treated of. Under each group of 

 subjects numerous trustworthy authorities are plainly referred to, so 

 that the latest discoveries and newest forms of apparatus are brought 

 under the student's notice. 



The examination ot Rocks themselves occupies Chapters X.-XX. 

 (pp. 84—265). First are briefly noticed " coarsely fragmental rocks ; " 

 then " ordinary stratified rocks,'* and " cleaved and foliated rocks," 

 " Igneous rocks," or those " that have consolidated from a state of 

 fusion," are more fully treated, under the headings (1) " glassy 

 rocks," (2) "lithoidal rocks," and (3) "distinctly holocrystalline 

 rocks." " Some physical characters of rocks " is the title of 

 Chapter XII. ; and " the chemical examination of rocks " that of 

 Chapter XIII. In the next chapter " the isolation of the constituents 

 of rocks " is carefully elaborated after the experiences of Cordier, 

 de Bellevue, Thoulet, Fouque, Harada, Delesse, Evans, and Smeeth. 

 The microscope and its use in petrological examination, with refer- 

 ences to Sorby, Wallich. Judd, Levy, Lacroix, and others, and a list of 

 the more important works treating of microscopic petrography, occupy 

 Chapters XY. and XVI. A careful description of " the characters 

 of the chief rock-forming minei'als [as seen] in the rock mass and in 

 thin sections" foUows (pp. 139-169). In Chapter XYIII. the 

 practical examination of the rocks themselves is entered upon. 

 Firstty, the sedimentary strata (pp. 170-196), such as i. Sands, 

 sandstones, grit-stones, gravels, pebble-gravels, conglomerates, and 

 quartzites : ii. Volcanic agglomerates, tuffs, ashes, and brecciated 

 lavas : iii. Clays and shales : it. Shell-limestone, coral-limestone, 

 nullipore-limcstone, oolitic limestone, dolomite, and brecciated lime- 

 stone : v. Bone-beds and phosphatic deposits : vi. Stalactites, 

 stalagmites, travertine, siliceous sinter, gypsum, rock-salt : vii. Con- 

 cretionary limestone, ironstone, also flint and chert : viii. Coal and 

 anthracite. Secondly, the petrology of the igneous rocks, as to 

 external (macroscopic) and internal (microscopic) appearances, is 

 treated (like the foregoing division) fo» amove, auH with references to 

 other workers, in a full chapter (pp. 196-250). These rooks are here 

 grouped as A. Holocrystalline : — granites and eurites ; syenites ; 

 quartz-dioritesaudquartz-aphanites; diorites and aphanites; oliviue- 

 gabbros and oliviue-dolcrites ; pcridotites. B. Hemicrystalline : 

 " Lithoidal rocks containing some glassy matter : " — rhyolites ; 

 trachytes and phonolites ; andesites ; basalts ; limburgites ; nephe- 

 linites and leucitites. C. " Highly glassy igneous rocks : " — obsi- 

 dians ; tachylytcs. A synoptical table, .^t p. 250, is intended to 

 give the above-mentioned grouping at a glance. 



Chapter XX. (pp. 251-265) is shorter, but carefully constructed 

 to treat of " Metamorphic rocks," both those " aflected by contact- 

 metamorphism," and those " affected by regional metamorjjhism." 

 Among the latter are — " crystalline limestones," " cleaved rocks," 

 and " foliated rocks." 



The palseontological relations of strata oc(ui)y the rest of thia 



