254 A. deF. Palmer^ Jr. — Condensation in the Steam Jet. 



lack of data regarding the distribution of pressure and specific 

 volume throughout the jet, and I have, therefore, reserved this 

 part of the work until measurements of these quantities can be 

 made. 



Turning now to the effect' of the actuating pressure, it is 

 obvious that both 



V,=/,(H,P)andV,=/,(D,P) 



increase with P. If f^ and f^ increase at the same rate, the 

 lowest points of the curves, similar to those of fig. 6, corre- 

 sponding to different pressures will be all on the same level. 

 If f^ increases faster than f^ the height of these points will 

 increase with the pressure. Finally if f^ increases faster than 

 /"j this height will decrease. The observations plotted in fig. 4 

 leave no doubt that the latter supposition is correct, and hence 

 the velocity of condensation must increase in marked degree 

 with the pressure. Furthermore since the initial velocity of 

 the jet and the rate of decrease of Y^ from the nozzle upward 

 increase with the pressure, it is to be expected that the ampli- 

 tude of the oscillations will decrease, and this expectation is 

 amply born out by the observations. 



Regarding the abrupt cessation of condensation, as at D and 

 F, fig. 6, Prof. Barus has suggested that it is possible that the 

 heat of instantaneous condensation may be sufiicient to super- 

 heat the advancing steam and thus destroy the supersaturation. 

 In support of this view it may be remarked that the probable 

 period of the oscillations is so short that very little heat escapes 

 from the jet, and that, the latent heat of steam being 540 and 

 its specific heat 0*5, suflScient heat is liberated by the condensa- 

 tion of one gram of steam to heat one gram of steam about 

 1000° c. 



In concluding I wish to express my thanks to Prof. Barus 

 for his kind suggestions and encouragement. 



Wilson Physical Laboratory of Brown University, July 1, 1896. 



