Abstract
American Journal of Science, November.—Elaboration of the fossil cycads in the Yale Museum, by L. F. Ward. The collection contains twenty-nine different species of cycads from the Black Hills, represented by nearly eight hundred specimens. A number of new species are described, and termed respectively Cycadeoidea superba, rhombica, heliochorea, utopiensis, reticulata, minima, and protea.—Chemical composition of turquoise, by S. L. Penfield. Turquoise is so uniform in its chemical constitution that it can hardly be considered an accidental mixture of an aluminium phosphate and a copper phosphate. Copper and iron must be regarded as constituents rather than impurities. The author derives it from ortho-phosphoric acid, in accordance with the formula
Article PDF
Rights and permissions
About this article
Cite this article
Scientific Serials . Nature 63, 169 (1900). https://doi.org/10.1038/063169b0
Issue Date:
DOI: https://doi.org/10.1038/063169b0