392 



KEPOET UNITED STATES GEOLOGICAL SURVEY. 



The following arrangement will give its probable composition. The 

 slight excess of sodinm over that requiredtocombine with the sulphuric 

 acid and chlorine is put in the form of sodinm orthosilicate (]^a4 Si O4.). 

 There are also traces of magnesium and calcium. 



Grains to imperial gallon. 



Sodium cliloride 13.650 



Sodium sulphate 11. 592 



Sodium orthosilicate 10.584 



Silica 16.191 



52. 017 



Pearl Geyser (Eo 68 on chart). — This supposed geyser is about 500 

 yards west of Echinus Geyser, in a wide flat space. It has a basin of 

 about twenty-five feet diameter, in which the bluish-tinted water had a 

 temperature of 162° when at a low point. The water fluctuates and 

 bulges at intervals. It is alkaline and chemical examination reveals 

 the following constituents : 



Grams to liter. 



Grains to impe- 

 rial gallon. 



Snlphnric acid 



Chlorine 



Silica 



Calcium 



Sodium 



0. 0328 



0.532 



0.112 



O.OOG 



0.349 



1. 0318 



2.296 



37. 240 



7.840 



0.420 



27. 580 



75. 376 



Arranging this, we get for probable composition 



Grains to imperial gallon. 



Calcium sulphate -t 1.400 



Sodium sulphate 1. 890 



Sodium chloride 61. 390 



Silica 7.840 



72. 520 



which is little more than a solution of common salt and silica. 



The bottle when opened was found to contain about two tablespoon- 

 fuls of a deposit of the consistence of soft-boiled Qgg, consisting largely 

 of silica. Under the microscope it was seen to be structureless, and 

 when heated upon platinum became a clear opaline-tinted mass. 



Opal Spring (No. 24 on chart, page 132). — This spring, which has the 

 comparatively low temperature of 90° F., is some distance north of Echi- 

 nus and Pearl Geysers, from which it is separated by a broad-topped hill. 

 It belongs to another group, and is on a mound of hard white silice- 

 ous sinter, which, close to the spring, has a coating of ocherish-colored 

 deposit. Tlie water is somewhat opalescent. The appearance can be 

 perfectly imitated by a solution of rosin in alcohol and water. It is 

 alkaline in reaction, and is composed of the following constituents : 



Grams to Uter. 



Grains to impe- 

 rial gallon. 



Sulphuric acid 



Chlorine 



Silica 



Calcium 



Sodium 



0.032 

 0.750 

 0.768 

 0. 034 

 0.401 



2.240 



52. 500 



53. 760 

 2.380 



31. 270 



