64 Analyses of Books. [July, 



Article XII. 



Analyses of Books. 



A Geological Classification of Rocks, with descriptive Synopses of 

 the Species and Varieties, comprising the Elements oj Practical 

 Geology. By John Macculloch, MD. FRS. FLS. Vice Pre». 

 Geol. Soc. &.c. &c. &c. 



It is probably known to our geological readers, that, except- 

 ing some very imperfect attempts towards a work, of this nature, 

 no classification and description of rocks has yet been published. 

 The want of one has been much felt by every geological student, 

 and the present publication is intended to supply it. 



Dr. Macculloch has adopted a geological plan for the classifi- 

 cation of rocks, and defends the superior advantages of it in an 

 argumentative chapter of some length at the commencement 

 of his book. Our readers are probably aware that the cele- 

 brated Brongniart had some time ago adopted a plan founded 

 on the mineral characters of rocks. Dr. M.'splan is, therefore, 

 similar to that of Werner, but he has made many important 

 variations in the arrangement, as well as some considerable 

 additions to the families of rocks. The principal difference in 

 his method of arrangement will be found in the divisions of 

 unstratified rocks which he has given, and which those who have 

 read his work on the Western Islands of Scotland would naturally 

 have expected to find. 



A number of preliminary chapters are occupied in general 

 details respecting the natural history and characters of rocks ; 

 and some space is also occupied in a plan for facilitating the 

 student's labours by collecting their general mineral characters 

 in certain groups, and in an account of the characters of the 

 classes into which rocks have been divided. 



The remainder of this work is occupied in the descriptions of 

 the families, and of all the varieties appertaining to each, which 

 the author seems to have thought requiring description, or 

 deserving of it. To give our readers a general notion of the 

 author's views respecting their families, or groups of rocks, we 

 subjoin his tabular view : , 



Primary Class. 



Unstratified. 

 Granite. 



Stratified. 

 Gneiss, Chlorite schist, 



Micaceous schist, Talcose schist, 



