58 J. C. Graham — Experiments with an Artificial Geyser. 



In these tables although the conditions are not precisely the 

 same, it is evident that in those cases in which the soap was 

 used, the periods between the eruptions were much shortened. 

 The differences in the temperature of the room and mercury, 

 and the changes in barometric pressure, are so slight as to be 

 unworthy of notice, or in a direction contrary to produce the 

 obtained result. It is also noticeable that the soap solution is 

 cooled much more after each eruption than is the case with 

 pure water. This is due to the fact that as the periods are 

 shorter, convection and other causes, could not operate so com- 

 pletely to heat the water in the geyser throat, and this cooler 

 water in rushing down at the end of the eruption, lowers the 

 general temperature. This factor also acts against the tend- 

 ency of the soap solutions having shorter periods, as it requires 

 a greater elevation of temperature at each eruption than is 

 required in the case of pure water. 



I think that these observations show conclusively that soap- 

 ing geysers does have a tendency to shorten their periods. 

 The question which now confronts us is : How does it pro- 

 duce this effect ? I will confess at once that I have not solved 

 this problem very satisfactorily ; but I have at least shown 

 that some theories which have been advanced as to the modus 

 operandi, cannot hold. 



It is evident that to bring about an eruption, what must be 

 done is to cause the water to boil at some point in the tube ; 

 and any effect which the soap has upon the boiling of the 

 geyser water may be a factor in the solution of the problem, 

 provided only the effect is in a positive direction. By being 

 in a positive direction, I mean having a tendency to hasten, 

 rather than to retard, the boiling. "What these various effects 

 are, I will now proceed to consider. 



First, as to the weight of the column. If the specific 

 gravity of the soapy water were much less than that of the 

 water alone this would lessen the pressure and so lower the 

 boiling point for any given depth. By determination, I found 

 that considering the water used of a specific gravity of 1, the 

 specific gravity of the soap solution was l'OOiS-i. The deter- 

 minations were in both cases at a temperature just below the 

 boiling point and the fluids were those actually used in operat- 

 ing the geyser. The effect of the difference of specific 

 gravities would therefore be negative as regards hastening an 

 eruption. 



Second, as to the boiling point itself. In this respect there 

 was no difference, it being 99° C. for both. These observa- 

 tions were made at the same time and with the same ther- 

 mometer, etc., to avoid all chances of error. 



