CALIFORNIA ACADEMY OF SCIENCES. 363 



From Death Valley. 



(26.) s. b. c. y. a. v. d. h. o. u>. Q. ;. z. t. y. x. v. ¥. U. 



e. g. r. on. 

 (27.) s. c. y. d. a. b. g. at. r. v. h. 

 (28.) W. U. s. 9. h. d. o. y. g. b. 



My former paper on the morphology of colemauite was read 

 at the California Academy of Sciences on the evening of October 

 6th, 1884. An abstract was printed in the Mining and Scientific 

 Press, of San Francisco, October 18th, 1884. On account of 

 delay in engraving the plates and printing, copies of Bulletin 

 No. II of the Cal. Acad, of Sci. were not received for distrib- 

 ution till early in January, 1885. 



On the 17th of October, 1834, Prof. Th. Hiortdahl presented 

 in the Vidensk.-Selsk. in Christiania, the results of his examina- 

 tion of some colemanite received from the Cal. State Mining 

 Bureau. 



Hiortdahl's axis ratio is: 



a : b : c = = 0.7747 : 1 : 0.5418 



3 = 110° 13' 



and the combination forms determined by him were twenty in 

 number, all of which are included in my original paper. Hiort- 

 dahl's analysis gave him boracic acid 47.64, lime 27.97, water 

 22.79, silica 1.28, ferric oxide and alumina 0.19, magnesia 0.13, 

 leading him to the formula Ca 3 B s J5 -f- 7 H O. This differs 

 somewhat from the formula set up by Mr. Evans, but the cause 

 of the difference evidently lies in the impurity of the material 

 which Hiortdahl had at his disposal . 



From the Verhandlungen des Natur-historichen Vereins des 

 preussichen Bheinlands und Westfalens for 1884, (published at 

 Bonn in 1885,) I copy the results of the chemical and optical 

 investigation of colemanite by Prof. Gerhard vom Rath and Dr. 

 C. Bodewig. The crystallographic results obtained by vom 

 Rath were communicated to the writer in a letter under date of 

 October 17th, 1884, and were added as Appendix II to my former 

 paper on colemanite. 



