Spheroidal Condition of Liquids. 259 



never attain, by several degrees, the temperature at which, 

 under ordinary conditions, they would boil, the reason of this 

 appears to me to be clearly explainable as follows: — 



Suppose heat to be applied to the dish represented in 

 fig. 2, then the particles constituting the inferior surface 

 of the liquid, being in contact with the dish, would abstract 

 from the dish the heat which is taken up in the process of 

 evaporation. But when the liquid is in the spheroidal state, 

 as represented in fig. 1, then the particles constituting the 

 inferior surface of the fluid being separated from the heated 

 dish, abstract the heat required to convert them into vapour, 

 not from the dish, as in the other case, but Jrom the rest of 

 the liquid, with which alone they are in contact. In other 

 words, the cooling influence of evaporation is in the one case 

 exercised upon the dish, and in the other case upon the liquid. 

 Hence, therefore, a liquid in the spheroidal state never can 

 attain the temperature at which it boils, because the more we 

 increase the heating action of the dish, the more we also in- 

 crease the cooling action of evaporation. 



This explanation is at variance with that propounded by 

 M. Boutigny, who accounts for the comparatively low tempe- 

 rature of the liquid spheroid, by ascribing to it a power of al- 

 most entirely reflecting heat from its inferior surface ; but this 

 hypothesis affords no explanation of the relationship which 

 unquestionably exists between the boiling-point of the liquid 

 and its maximum temperature in the spheroidal state. Be- 

 sides, if reflexion of heat prevented increase of temperature, 

 it would also prevent evaporation, which it clearly does not ; 

 for, when the dish is highly heated, the water evaporates with 

 considerable rapidity, although its sensible heat remains con- 

 stant at 7° below the boiling-point. 



It is said, and I have no doubt of the fact, that when a 

 liquid heated to the boiling-point is poured into a dish suffi- 

 ciently hot to produce the spheroidal state, the temperature 

 of the liquid immediately recedes to the point which it would 

 have attained if the liquid had been placed in the dish with- 

 out being previously heated. Now this effect is fully accounted 

 for by the cooling action of evaporation operating in the man- 

 ner I have described, but it is perfectly inexplicable on the 

 hypothesis of reflexion of heat. 



I repeated M. Boutigny's beautiful experiment of plunging 

 a mass of red-hot platina into a glass of cold water, in which 

 the metal remains incandescent for several seconds after the im- 

 mersion, and is seen invested with an atmosphere of steam. 

 In this experiment there is no ebullition of the water, notwith- 

 standing that the steam has no outlet such as it has when the 



lb 2 



