Scientific Serial

Abstract

American Journal of Science, December.—The geology of the Little Colorado Valley, by Lester F. Ward. The paper is accompanied by a section showing 3500 feet of Trias, of which 1200 are Painted Desert beds, 1600 Shinarump beds, and 700 Moencopie beds.—On pyrite and marcasite, by H. N. Stokes. It is pointed out that although there is no difficulty in distinguishing these two minerals in well-crystallised specimens, there remains a residuum consisting of massive or finely grained material in which this is not possible. The methods which have been proposed for such cases are criticised and found to be insufficient. A method has therefore been developed in which advantage is taken of the difference between the two sulphides in their behaviour towards solutions of ferric ammonia alum, and it has been found possible to apply this to determine the amount of each in mixtures. The, application of this process to various samples of doubtful nature, especially of concretions, has shown that the finely fibrous specimens usually passing as marcasite are very commonly pyrite.—Studies of Eocene mammalia in the Marsh collection, Peabody Museum, by J. L. Wortman.—The dielectric constant of paraffin, W. G. Wormwell. Four samples of commercial paraffin were examined with a modified form of the Blondlot oscillator, the refractive index for the D line of the samples being also determined. The dielectric constant of a given paraffin increases with the density of the paraffin. It augments rapidly from a temperature 20° above the melting-point to a temperature 30° below the melting-point, and among different paraffins the dielectric constant increases with a rise in the melting-point. A comparison of the results for short electrical waves and short light waves shows that Cauchy's formula as a means of obtaining the index of refraction for indefinitely long waves does not meet the experimental data.—On some new mineral occurrences in Canada, by G. C. Hoffman.—The estimation of molybdic acid reduced by hydriodic acid, by F. A. Gooch and O. S. Pulman, jun. The conditions under which molybdic acid may be accurately determined by reduction with potassium iodide and hydrochloric acid are here laid down, and test analyses showing the accuracy of the method are cited.—The Veramin meteorite, by H. A. Ward. The meteorite consisted of an intimate mixture of metal and mineral, in roughly equal proportions. Analysis of the metallic portion is given.