APPENDIX I. 



In May, 1884, Prof. Gerhard von Rath, of the University of 

 of Bonn, Germany, was in San Francisco, and obtained a speci- 

 men of colemanite which he showed me at the time, stating that 

 it was given to him as a new mineral, but that its general appear- 

 ance was so similar to datholite that he was inclined to think it 

 was that mineral. The matter had passed from my mind when 

 Mr. Evans brought me his crystal of colemanite, and it was not 

 until I had finished my examination, and was ready to publish 

 my preliminary notice, that the identity of the mineral I had 

 been examining with that shown me by von Rath occurred to me. 

 I at once sent my results to von Rath, who had in the mean 

 time arrived at his home from his long American tour. A slight 

 examination had shown him that his specimen was not datholite. 

 and he at once proceeded with a crystallographic determination. 

 When my letter reached him, he had obtained the following 

 results which he very kindly sent me with permission to publish. 

 Prof, von Rath's crystal coutained the forms: s (oc P), t (oo P 2), 

 n (oo P oo), m (oo P oo), g (0 P), h (2 P oo), b (— P), y (P). v (2 P), 

 c (P oo), a (2 P oo), d (2 P 2), and a (— 3 P). From the funda- 

 mental angles 



s : s (oo P : oo P) = 107° 50' 



g :s(0 P : oo P) = 106 16 

 g :c(0 P : P oo) = 153 4 



the following axial elements were determined: 



a : h : c = 0.7769 : 1 : 0.54162 

 j3 = 69° 43' 20" 



The following angles were calculated from these elements (a 

 few measured being added in parenthesis): 



6 : n = 134° 22^' v : h = 144° 9 ' 



b :m = 109 54£ v : y = 154 50£ 



b : g = 146 18 (meas'd 154 50) 



(meas'd 146 17) a : n = 104 4 



c :n = 107 59| a : m == 135 27^ 



