Igneous Rocks and their Origin, R. A. Daly, New York, 1914. Footnote 132: Among these may be mentioned: Rosenbusch u. Wülfing, Physiog. der petrog. wicht. Min., Stuttgart, 1905. Iddings, J. P., Rock-Minerals, 1st ed., New York, 1906. Johannsen, A., Manual of Petrographic Methods, New York, 1914. Winchell, N. H. and A. N., Elements of Optical Mineralogy, New York, 1909. Footnote 133: We may mention here, for example, the work in mineralogy of Penfield, noticed in the accompanying chapter on mineralogy. In addition to the accurate determination of the composition and constants of many minerals, some of which have importance from the petrographic standpoint, we owe to him more than anyone the recognition of fluorine and hydroxyl in a variety of species, and thereby the perception of their pneumatolytic origin. His papers have been published almost entirely in the Journal. Footnote 134: Wright, Methods of Petrographic-Microscopic Research, Carnegie Inst., Washington, 1911, and various papers; many in the Journal. Footnote 135: Conf. Wright’s work quoted above and the various manuals previously mentioned. Footnote 136: Kemp, Hand-book of Rocks, 3d ed., New York, 1904. Pirsson, Rocks and Rock-Minerals, New York, 1910. Footnote 137: Williams, G. H., U. S. Geol. Surv., Bull. =62=, Washington, 1890. Footnote 138: Van Hise, Treatise on Metamorphism, U. S. Geol. Surv., Monograph =17=. Footnote 139: F. W. Clarke, U. S. Geol. Surv., Bull. =591=, 1915. Footnote 140: Hillebrand, Analysis of Silicate and Carbonate Rocks, U. S. Geol. Surv., Bull. =422=, 1910. Footnote 141: Washington, Chemical Analysis of Rocks, pp. 200, New York, 1910. Footnote 142: Id., Chemical Analyses of Igneous Rocks (1884–1900), U. S. Geol. Surv., Prof. Paper, No. =14=, 1903. Footnote 143: Osann, Beitr. zu chem. Petrogr., II Teil. Anal. d. Eruptivgest., 1884–1900, Stuttgart, 1905. Footnote 144: Washington, ibid., 2d ed., U. S. Geol. Surv., Prof. Paper =99=, pp. 1216, 1917. Footnote 145: Clarke, U. S. Geol. Surv., Bull. =616=, 1916. Footnote 146: Fouqué and Michel-Lévy, Synthese des Mineraux et des Roches, Paris, 1882. Footnote 147: Morozewicz, Exper. Untersuch. u. Bildung der Min. im Magma, Min. petr. Mitt., =18=, 1898. Footnote 148: Doelter, Synthetische Studien, N. Jahrb. Min. 1897, =1=, 1–26. Allg. chem. Mineralogie, etc. Footnote 149: Tamman, Krystallisieren und Schmelzen, 1903. Footnote 150: St. Meunier, Les Méthodes de Synthèse en Minéralogie, Paris, 1891. Footnote 151: Vogt, Mineralbildung in Smelzmassen, Christiania, 1892; Silikatschmelzlösungen, =1= and =2=, 1903, 1904, and various other papers, esp. in Min. petr. Mitt., vols. =24= and =25=, 1906. Footnote 152: H. E. Boeke, Grundlagen der physikalisch-chemischen Petrographie, Berlin, 1915.