Nat emes | Tea Sacie aaies ae 
66 Scientific Intelligence. 
method of classification adopted is as follows:—(i) orthoclase 
rocks ; (2) orthoclase-nepheline, and orthoclase-leucite rocks; (3) 
plagioclase rocks; (4) plagioclase-nepheline, and plagioclase-leu- 
cite rocks; (5) nepheline rocks; (6) leucite rocks; (7) olivine, or 
chrysolite rocks. The special system of ercesiaarn ot thes se 
ular, syenites, or (2) Abe porphyries ‘with no ‘iit 
Secondly, the younger rocks (I) ie a * sore. and are (1) gran- 
ular or porphyritic, liparites, or (2) glussy, obsidian, trachytic 
pitchstone, perlite, eooreeds or Ries are (II) without quartz, includ- 
“— the trachytes and e glassy rocks 
The description of the i individual rocks are very a ieee espe- 
cially the references to their microscopic character. valuable 
portion of the work is the list of books and memoirs on nef aeraan 
cal subjects covering about thirty pages. E. 8. D. 
7. A Guide to 
oe of Rocks, being an intro- 
duction to Litholo ee by E. Janyeraz. Translated from the 
French by G. W. Pl mpton, C.E., A.M. 165 pp. 8vo. New 
see 1877. (D. Van Nostrand.)—This little book has some very 
escribed as due to the ‘ ria eay of fragments of the rock 
in which wos — found,” (p. 36); pyrites (FeS,) j is said to be 
reduc o FeS (p 109) ete. Besides, such words as 
Cordveritfels, Cavite, lopfstein, Gallinace, ete., do not belong 
to the English language. 
8. Zubles for the Determination of Minerals. Based upon the 
tables of Weisbach; enlarged, and furnished with a set of mineral 
formulas, a column o: of 8 specitic gravities and some of the character- 
istic blowpipe reactions; by Persiror Frazer, Jr., A.M. 119 pp. 
8vo, Philadelphia, 1878. _(- B. Lippincott ’& Co ne —The first 
‘eine ix of this J urnal. e revised wor ides numerous cor- _ 
rections and minor sadieign ns, contains s some new fe. atures, as for 
instance, the indication of the comparative rarity of the less 
aes species 
_ 9. Tridymite in Ireland.—Prof. A. von Lasaulx reports the dis- 
covery, of tridymite in the trachyte-porphyry of onl Antrim, 
10. Anihracite of Pennsylvania.—Mr, E. T, Hardman, in a 
n the Journal of the Royal Geological Society of Ireland 
= 200, 1876), attributes the change to anthracite in eatin 
series of trap-dikes to the eastward—not tec 
ae at that these upriibes are Triassic or Jurassic in yin pe 
the nearest over fifteen miles distant from the coal. 
