SOAPING GEYSERS. 157 



and boils, ex('e[)t iininediatoly after au eruption. The intervals be- 

 tween eraptions vary somewhat from year to year; but at the time of 

 these experiments the action was fairly regular, t\n) geyser playing 

 every four hours. [ was successful in obtaining an eruption (juite equal 

 to the natural displays, which throw a column of water oU feet into 

 the air. Here at the Monarch there is no surface reservoir, and the 

 narrow fissure, filled with loose blocks of rocks around which the 

 water is in constant agitation, prevents all measurements of depth. 



Tlie results of the many experiments, not only upon active geysers 

 but upon a large number of hot springs, determine fairly well the 

 essential conditions which render it possible to bring about geyser 

 action by artificial means. Negative results are frequently as valuable 

 for this inquiry as experiments yielding imposing displays. 



Outside of a few exceptional instances, which could not be repeated, 

 and in which action was probably only anticipated by a few minutes 

 in time, geyser eruptions produced by soap or alkali appear to demand 

 two essential requirements: First, the surface caldron or reservoir 

 should liold but a small amount of water, exposing only a limited area 

 to the atmosphere; second, the water should stand at or above the 

 boiling point of water for the altitude of the geyser basin above vsea 

 level. The i)rincipal factor which makes it possibles to cause an 

 eruption artificially is, I think, the super-heated and unstalde condi- 

 tion of the surface waters. Many of the geysers and hot springs pre- 

 sent singular phenomena of pools of water heated above the theoret- 

 ical boiling point, and, unless disturbed, frequently remain so for 

 many days without exhibiting any signs of ebullition. It may not be 

 easy to describe accurately these super-heated waters; but anyone 

 who has studied the hot springs and pools in tlie Park and carefully 

 lujted the tem[)eratures, (juickly learns to recognize the peruliar i\\). 

 pearance of tliese basins when heated above the boiling point. They 

 look as if they were "ready to boil," except tliat tlie surface remains 

 placid, oidy interrupted by numerous steam-bubbles, rising through 

 the water from below and bursting (|uietly upon reaching the surface. 



Marcet, the French physicist, lias specially investigated the phenom- 

 ena of super-heated waters, and has succeeded in attaining a tcmjjera- 

 tureof 105° ('. befm-e ebullition. Super-heated waters in nature, how- 

 ever, appear to have been scarcc^ly recognized, except during the prog- 

 ress of the work in the Velh)wstone Park, in connection with a study 

 of the geysers. The altitudes of the geyser basins above sea-level 

 Inive been ascertained by long series of barometric readings, contin- 

 ued through several seasons. In conducting a series of observations 

 i.pon th(^ boiling ))oints of th(i thermal waters in the Park, Dr. Wil- 

 liam Ilallock, who had charge of this special investigation, deter- 

 mined the theoretical boiling-point by noting the mean daily readings 

 oC the mercurial colum!i. The exact boiling-point of a i)ure surface- 

 water, obtained from a neighboring mountain stream and the boiling- 



