

Day and Sosman — Melting Points of Minerals. 349 



% The purest natural albite showed signs of melting when heated a few 

 minutes at 1200°, and again when heated for four hours at 1100°. Small 

 amounts of certain impurities might, however, lower the melting point con- 

 siderably, while others would raise it. No determinations of melting point 

 on chemically pure albite or orthoclase have been made. The best statement 

 that can be made, therefore, is to say that the melting point is probably 

 below 1200°. The facts concerning microline are similar. 



** These temperatures differ from the others in the tables, in not being 

 fixed physical points. The change is from an unstable into a stable form 

 and is not reversible. The figures merely represent the temperatures at 

 which the change is rapid enough to become observable within a reasonable 

 length of time. 



§ Both of these have been called kupfferite by different authors. 



References. 



I. The Isomorphism and Thermal Properties of the Feldspars. I. Ther- 

 mal Study ; by Arthur L. Day and E. T. Allen. II. Optical Study ; by J. 

 P. Iddings, with an introduction by George F. Becker. Publication No. 31, 

 Carnegie Institution of Washington (1905). 



4. Der Isomorphismus und die thermischen Eigenschaften der Feldspate. 

 Arthur L. Day and E. T. Allen. Zts. physikal Chem., liv, 1-54, 1905. 



6. On VVollastonite and Pseudo-Wollastonite, Polymorphic Forms of Cal- 

 cium Metasilicate. E. T. Allen and W. P. White, with Optical Study by 

 Fred. Eugene Wright. This Journal (4), xxi, 89-108, 1906. 



7. Quartz Glass. Arthur L. Day and E. S. Shepherd. Science, N. S., 

 Vol. xxiii, No. 591, pp. 670-672, 1906. 



8. The Lime-Silica Series of Minerals. Arthur L. Day and E. S. Shep- 

 herd. Jour. Am. Chem. Soc, xxviii, 1089-1114, 1906. 



II. The Lime-Silica Series of Minerals. Arthur L. Day and E. S. Shep- 

 herd, with Optical Study by Fred. Eugene Wright. This Journal (4), xxii, 

 265-302, 1906. 



13. Minerals of the Composition MgSi0 3 ; a Case of Tetramorphism. 

 E. T. Allen, Fred. Eugene Wright, and J. K. Clement. This Journal (4), 

 xxii, 385-438, 1906. 



19. Die Kalkkieselreihe der Minerale. Arthur L. Day, E. T. Allen, E. S. 

 Shepherd, W. P. White and Fred. Eugene Wright. Tschermak's Min. 

 Petr. Mitt., xxvi, 169-232, 1907. 



32. Diopside and its Relations to Calcium and Magnesium Metasilicates. 

 E. T. Allen and W. P. White ; with Optical Study by Fred. Eugene Wright 

 and Esper S. Larsen. This Journal (4), xxvii, 1-47, 1909. 



39. Quartz as a Geologic Thermometer. Fred. Eugene Wright and Esper 

 S. Larsen. This Journal (4), xxvii, 421-447, 1909. 



41. The Binary Systems of Alumina with Silica, Lime, and Magnesia. 

 E. S. Shepherd and G. A. Eankin ; with Optical Study by Fred. Eugene 

 Wright. This Journal (4), xxviii, 293-333, 1909. 



44. Melting Point Determination. Walter P. White. This Journal (4), 

 xxviii, 453-473, 1909. Melting Point Methods at High Temperatures. 

 Walter P. White. Ibid. (4), xxviii, 474-489, 1909. 



46. The Nitrogen Thermometer from Zinc to Palladium. Arthur L. Day 

 and Robert B. Sosman ; with an Investigation of the Metals by Eugene T. 

 Allen. This Journal (4), xxix, 93-161, 1910. 



54. The Platinum-Rhodium Thermoelement from 0° to 1755°. Robert B. 

 Sosman. This Journal (4), xxx, 1-15, 1910. 



56. The Thermal Dissociation of Calcium Carbonate. John Johnston. 

 Jour. Amer. Chem. Soc.,xxxii, 938-946, 1910. 



61. Preliminary Report on the Ternary System CaO- Al 2 3 -Si0 2 ; a 

 Study of the Constitution of Portland Cement Clinker. E. S. Shepherd and 

 G. A. Rankin ; with Optical Study by Fred. Eugene Wright. J. Ind. and 

 Eng. Chem., iii, 211-227, 1911. 



64. Quarz als geologiscb.es Thermometer. F. E. Wright and E. S. Lar- 

 sen. Zts. anorg. Chem., lxviii, 338-369, 1910. 



65. Die binaren Systeme von Tonerde mit Kieselsaure, Kalk, und Mag- 

 nesia. E. S. Shepherd and G. A. Rankin. Nebst optischen Untersuchun- 

 gen von F. E. Wright. Zts. anorg. Chem., lxviii, 370-420, 1910. 



