REPORT ON NATIONAL MUSEUM. 163 



On the determination of feldspars in thin sections of rocks. 



(Proc. Nat. Mua., 1881, iv, pp. 134-136.) 



The author gives as the result of his experience that grave errors are liable 

 to arise through relyiug altogether upon optical methods for determining 

 feldspars in thin sections, since, owing to the uncertain angle at which the 

 crystals are cut, it is not only not possible at all times to distinguish with 

 certainty between the different varieties of plagioclase, but at times they can 

 with great difficulty be distinguished from orthoclase. 



On a phosphatic sandstone from Hawthorne, Fla. 



(Proc. U. S. Nat. Mus., 1882, v, pp. 46-48.) 



Gives the results of microscopic and chemical analysis of a phosphatic 

 sandstone from Hawthorne. The stone was found to contain some 16 per 

 cent, of phosphoric acid. 



Brief abstracts and reviews of papers by American authors, published by 

 Br. Hawes in the Neues Jahrbuch fUr Mineralogie, Geologic, und Pala- 

 eontologie. 



B. J. Harrington. Notes on chrome-garnet, phyrhotite, and 

 titaniferous iron ore. Proc. Canadian Natural History Society, 

 May, 1880. — H. B. Cornwall. Gallium in American blende. 

 Am. Chem. Jour., April 1880, p. . — Peter Collier. Analysis 

 of a mineral resembling thorite. Jour. Amer. Chem. Soc, xi, 

 ii, p. 73. — F. W. Clark and M. E. Owens. On a new variety of 

 tetrahedrite. Am. Chem. Jour., June, 1880, p. 173. 



(Neues Jahrbuch, 1881, xi, ii pp. 174-175.) 



George J. Brush. On American sulpho-selenides of mercury 

 with analysis of onofrite from Utah, by W. G. Comstock. 

 Am. Jour. Science, xvi, April, 1881.— F. A. Genth and W. C. 

 Kerr. The minerals and mineral localities of North Carolina, 

 being Chapter i of Vol, ii of the Geology of North Carolina, 

 p. 122. Ealeigh, 1881.— Henry C. Lewis. On Philadelphite, a 

 new mineral species. Proc. Phil. Acad. Nat. Sciences, Decem- 

 ber 22, 1879. — Wm. P. Blake. Occurrence of realgar andorpi- 

 ment (auripigment) in Utah Territory. Am. Jour. Science, 

 March, 1881, p. 219.— W. E. Hidden. On the Whitfield County, 

 Georgia, meteoric iron. Am. Jour. Science, April, 1881, 

 p. 287 



(Neues Jahrbuch, 1881, xi, iii, pp. 337-343.) 



A. E. C. Selwyn. Geological survey of Canada ; report of progress 

 for 1878-'79. — D. Honeyman. Geological waifs from the Mag- 

 dalen Islands. — D. Honeyman, D. C. L. Nova Scotia geology. 

 Notes on a new geological map of Pictou County. Proceedings 

 and Transactions of the Nova Scotia Institute of Natural 

 Sciences, Halifax, 1880, Vol. v, pp. 119, 136, 192.— Eugene A. 

 Smith On the geology of Florida. Am. Jour. Science, April, 

 1881, p. 292.— Geo. M. Wheeler. Annual Eeport upon the 

 Geographical Survey of the Territory of the United States 

 west of the 100th meridian. Appendix OO of the Annual 



