Some Recent American Penological Literature. 227 



" The Ternary System CaO-MgO-Si0 2 ," by J. B. Ferguson and 

 H. E. Merwin. Proc. Nat. Acad. Sci., vol. v, pp. 16-18, 1919. 

 A very brief summary of a hitherto undescribed portion of this 

 system by the quenching method. The phases found include, among 

 others, cristobalite, tridymite, pseudowollastonite, periclase, forsterite, 

 mouticellite, diopside, and various solid solutions. One hitherto 

 unrecorded compound is probably akermanite. The temperature- 

 concentration relations are shown in a triangular diagram. 



"Temperature Viscosity Relations in the Ternary Svstem CaO- 



A] 2 O s -Si0 2 ," by A. L. Field & P. H. Royster. Trans. Amer. 



Inst. Min. Eng., vol. lviii, pp. 658-68, 1918. 



A study of the viscosity of slags, with reference to blast-furnace 



work. Measurements of viscosity show the existence of definite 



compounds in slags and even indicate their fields of stability. The 



maxima of viscosity occur at quintuple points and the minima at the 



binary eutectics. 



" The Significance of Glass-making Processes to the Petrologist," by 



N. L. Bowen. Journ. "Wash. Acad. Sci., vol. viii, pp. 88-93, 



1918. 



Observations during war-work at the Bausch-Lomb glass plant 



are applied to elucidate inhomogeneity in silicate melts. Liquid 



immiscibility and the Gouy-Chaperon principle are regarded as 



inapplicable, and differentiation is referred to rising of crystals and 



sinking of heavy liquid. 



' ' A Type of Igneous Differentiation," by F. F. Grout. Journ. Geol., 

 vol. xxvi, pp. 626-58, 1918. 

 The rocks of the Duluth intrusions fall into two series, gabbroid 

 and granophyric (red rock). The evidence suggests an immiscible 

 separation of acid and basic portions, the variations in the gabbro 

 being produced by convection. The evidence is strong that 

 differentiation of two kinds may occur in a single magma-chamber. 



"The Lopolith : an Igneous Form exemplified by the Duluth 

 Gabbro," by F. F. Grout. Amer. Journ. Sci., vol. xlvi, 

 pp. 516-22, 1918. 

 The Duluth gabbro differs from typical laccoliths in that its 

 central part is sunken, not raised. It is about 140 miles across, 

 covering an area of about 15,000 square miles, and its volume is 

 estimated at 50,000 cubic miles. It is intruded along the base of the 

 Keweenawan. It is compared to the igneous masses of Sudbury and 

 the Bushveld, and possibly of Skye and Julianehaab. For such saucer- 

 shaped masses the name " lopolith" is suggested. 



"The Charnockite Series of Igneous Rocks," by H. S. "Washington. 

 Amer. Journ. Sci., vol. xli, pp. 323-38, 1916. 

 Analyses, supplementary to Holland's descriptions, are given of 

 five specimens of typical rocks of the Charnockite series, selected by 

 the Indian Geological Survey. The relations of the Charnockites to 

 the rocks of similar petrographic provinces are discussed somewhat 

 fully. 



