188 GEOLOGICAL SURVEY OF THE TEEEITOEIES. 



Geyserite from New Zeland, f analysis hy Fattison.J 



fPliil. Mag., m, xsv, 495.] Specific gravity, 1.968. 



Silica 77. 35 



Alumina 9, 70 



Sesquioxide of iron 3. 72 



Lime 1.54 



Water 7. 66 



99.97 



Geyserite from New Zeland, (analysis hy Mallet. J 



[PMl. Mag., rV, V. 285.] Speciiic gravity, 2.031. 



Silica 94. 20 



Alumina - 1. 58 



Sesquioxide of iron 0. 17 



Lime - Indication. 



Chloride of sodium ^ 0. 85 



Water .' 3. 06 



99.86 



On the 6th of August we 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 

 passed by Madison Lake, which is about five miles in diameter. It is 

 heart-shaped. The sand on its shore is composed of fiuely-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, whose 

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

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

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

 perature from 1150 ¥. to 191° F., averaging 166 Jo F. ; the latter ranged 

 from 132° F. to 190° F., the average being 155^° F. The temperature 

 of the air during observation was about 65° 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 temperature 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 IGOo F. The mud springs or geysers, for they threw the mud 



