188 GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 



Geyserite from Neic Zeland, f analysis hy Pattison.J 



fPhil. Mag., HI, xxv, 495.] Specific gravity, 1.968. 



Silica 77. 35 



Alumina 9. 70 



Sesqiiioxide of iron ^ 3. 72 



Lime 1. 54 



Water 7. G6 



99.97 



Geyserite from New Zeland, f analysis hy Mallet. J 



[Phil. Mag., TV, V. 235.] Specific gravity, 2.031. 



SiUca 94. 20 



Alumina 1. 58 



Sesquioxide of iron 0. 17 



Lime Indication. 



Chloride of sodium •. . . 0. 85 



Water 3. 06 



99.86 



On the Gth of August Tve bade farewell to the Geyser Basin and 

 started on our way toward the Yellowstone Lake to rejoin the main 

 party. Our way led upward through dense timber, and after traveling- 

 eight miles we reached the summit of the first ridge of mountains sepa- 

 rating us from the lake. The rock at the summit was a porphyritic 

 obsidian, containing large crystals of feldspar thickly disseminated 

 through it. We now began to descend, and at the foot of the mountain 

 X)assed by Madison Lake, which is about five miles in diameter. It is 

 heart-shaped. The sand on its shore is composed of fihely-broken-up 

 obsidian, intermixed with chips of chalcedony and red jasper. We were 

 obliged to go into camp at night without having reached the lake, whoso 

 shore, however, we reached the following morning, to find ourselves 

 about three miles below camp. Our cam^) was situated near a large 

 collection of hot springs and mud-geysers. The former varied in tem- 

 perature from 1150 r. to 191° F., averaging IGG^V^ F. j the latter ranged 

 from 1320 F. to 190^ F., the average being 155|o F. The temperature 

 of the air duriug observation was about 05^ F. The water of the springs 

 contained — 



Silica, 



Iron, 



Alumina, 



Soda, 



Potassa, 



Sulphuric acid. 



Its reaction was neutral. In some of the springs of low temj^erature there 

 was a red gelatinous organic growth. One of the most curious of the 

 springs was situated in the midst of the lake, close to the shore. Its basin 

 was about 3 feet above the surface of the lake, and was composed of a 

 white deposit containing a large percentage of silica, it being of the same 

 character as the deposit about the springs on the shore. The water in 

 this basin, which had the shape of a truncated cone, had a tempera- 

 ture of 160° F. The mud springs or geysers, for they threw the mud 



