PETROLOGICAL ABSTRACTS AND REVIEWS 187 
Miter, WittiAm J. Geology of the Lake Pleasant Quadrangle, 
Hamilton County, New York. Bull. 182, New York State 
Museum, 1916. Pp. 75, pls. 10, figs. 4, map 1. 
Geologic and physiographic history of the region, together with 
petrographic descriptions of various anorthosite-gabbros, syenites, 
granites, granite- and syenite-porphyries, gabbros, and diabases. 
Mosss, A. J. “A Scheme for Utilizing the Polarizing Microscope 
in the Determination of Minerals of Non-Metallic Lustre,” 
School Mines Quart., XXXIV (1913), No. 4, pp. 30. 
A very useful series of tests which may be applied to the determina- 
tion of minerals as a supplement to the usual tests before the blowpipe, 
etc. After describing the general methods of procedure, the writer 
gives a 19-page key based on taste, flame-color, fusibility, and efferves- 
cence or gelatinization with acid, and final optical tests based on refrac- 
tive index, interference color, optical character, and miscellaneous 
characteristics. 
Nicci, Paut. “The Phenomena of Equilibria between Silica 
and the Alkali Carbonates,” Jour. Amer. Chem. Soc., XXXV 
(1913), 1003-1727. 
O’NErL1, J. J. St. Hilaire (Beloeil) and Rougemont Mountains, 
Quebec. Canada Dept. Mines, Mem. 43, Geol. Series 36, 
Ottawa, 1914. Pp. 1c8, map 1, bibliography. 
Rising out of the plain to the east of Montreal is a series of isolated 
hills representing volcanic necks or laccoliths. They have been called 
the Monteregian Hills and may be tabulated as shown on page 188. 
After giving a short account of the geology of the whole region, the 
author takes up the structural features of St. Hilaire and Rougemont 
mountains, and concludes from the evidence of undisturbed country- 
rock, of the coarse texture of the igneous mass close to the outer contact, 
of the vertical conduit through which the magma passed, of the develop- 
ment of flow texture in the essexite, and of the brecciation shown in the 
syenite at the contact, that St. Hilaire is an eroded volcanic neck. The 
evidence at Rougemont Mountain is not so positive. The coarse texture 
at the contact, which is wavy without regard to topography, and the 
cliff development on two sides seem to indicate that the conduit was 
