RECENT ADVANCES IN SCIENCE 385 



Loughlin, G. F., The Oxidised Zinc Ores of Leadville, Columbia, U.S. Geol. 



Survey, Bull. 681, 19 19, 91. 

 Nason, F. L., Characteristics of Zinc Deposits in North America, Trans. Amer. 



Inst. Mm. Eng, 191 8, 57, 830-62. 

 Pardee, J. T., Geology and Ore Deposits of the Coalville Indian Reservation, 



Washington, U.S. Geol. Survey, Bull. 677, 1919, 186. 

 Knopf, A., Geology and Ore Deposits of the Yerington District, Nevada, U.S. 



Geol. Survey, Prof. Paper, 114, 191 9, 68. 

 Lindgren, W., and Loughlin, G. F., Geology and Ore Deposits of the Tintic 



Mining District, Ibid., Prof. Paper, 107, 1919, 282. 

 Bastin, E. S. and Laney, F. B., The Genesis of the Ores at Tonopah, Nevada, 



Ibid., Prof. Paper, 104, 1919, 50. 

 Leffingwell, E. de K., The Canning River Region, Northern Alaska, U.S., 



Ibid., Prof. Paper, 109, 19 19, 251. 

 Miller, B. L. and Singewald, J. T., The Mineral Deposits of South America, 



(New York : McGraw Hill Book Company, 1919), 589. 

 Whitehead, W. L., The Veins of Chaharcillo, Chile (silver), Econ. Geol., 1919, 



14, 1-45. 

 Krusch, P., Die nutzbaren Lagerstatten Belgiens, ihre Geologische Position und 



wirtschaftliche Bedeutung, " Gluckauf? Essen, 1916, 75. 

 Beyschlag, F., Die Mineral " Reichtum " der Turkei, Zeitsch. f. Prakt. Geol., 



1918, 81-8. 

 Berg, G., Uber die Begriffe vados und juvenil und ihre Bedeutung fur die Lager- 



stattenlehre, Ibid., 23-8. 

 Lahee, F. H., Geologic Factors in Oil Prospecting, Econ. Geol., 1919, 14, 480-90. 

 Kemp, J. F., Observations on a Florida Sea Beach with Reference to Oil Geology, 



Ibid., 302-23. 

 Matteson, W. G., A Review of the Development in the New Central Texas Oil- 

 fields during 1918, Ibid., 95-146. 

 Bagg, R. M., Fluorspar in the Ordovician Limestone of Wisconsin, Bull. Geol. 



Soc. Amer., 191 8, 29, 393-8. 

 Phillips, W. B., The Sulphur Deposits in Culberson Co., Texas, Trans. Amer. 



Inst. Min. Eng., 1918, 58, 265-83. 

 Crandall, R., Notes on the Geology of the Diamond Region of Bahia, Brazil. 



Econ. Geol., 1919, 14, 220-44. 



MINERALOGY AND CRYSTALLOGRAPHY. By Alexander 

 Scott, M.A., D.Sc. 



An elaborate account of crystal optics is given by J. Becken- 

 kamp (Statische und kinetische Kristalltheorien, 2, pp. 1-523, 

 191 5). The second part of the same volume (pp. 524-646) is 

 occupied by a discussion of the relationships between the 

 various polymorphic modifications of silica, especially quartz 

 and tridymite. The relative specific gravities, double refrac- 

 tion, and so forth, are explained on the basis of the crystal 

 structure (cubo-octahedral) assigned to the two minerals ; the 

 analogous relationships between pyrites and marcasite are 

 also considered. The optical effects observed when plates of 



