'258 Mr. W. G. Armstrong on the 



If instead of water we use a liquid that boils at a lower tem- 

 perature than water, then similar effects are obtained at a re- 

 duced temperature of the dish. Thus if the dish be not suf- 



Fig. 1. Fig. 2. 



ficiently hot to sustain water in the spheroidal state, it will still 

 be sufficiently hot to sustain spirit of wine in that state ; and 

 again, when it is too cool for spirit of wine, it may still have 

 sufficient heat to produce the effect with aether. On the other 

 hand, if the boiling-point of the liquid be higher than that of 

 water, then it is necessary lo increase the temperature of the 

 dish, in order to produce the spheroidal state. But whatever 

 the boiling-point of the liquid may be, the maximum tempe- 

 rature it attains in the spheroidal form is always several de- 

 grees below the temperature at which ebullition takes place. 



It is obvious, therefore, that the cause which limits the 

 temperature of the liquid spheroid, as well as that which oc- 

 casions its separation from the heating surface, has an intimate 

 connection with the boiling-point of the liquid. This circum- 

 stance affords a strong presumption that the effects are in 

 both cases in some way or other attributable to evaporation ; 

 and I shall now endeavour to explain the phaenomena in con- 

 formity with this view of the subject. 



It is easy to conceive that the radiant heat of a red-hot dish, 

 into which water is poured, will be sufficiently powerful to 

 vaporize the inferior surface of the water before it comes into 

 actual contact with the dish ; and it is obvious that the vapour, 

 resulting from such an action of the heat, must necessarily 

 find a place between the water and the dish, so as to prevent 

 their nearer approximation. The weight of the liquid will 

 tend to displace the interposing steam, but the continued eva- 

 poration will maintain the separating stratum so long as the 

 dish remains sufficiently hot to vaporize the water without 

 actual contact. 



The absence of ebullition, which also characterizes the 

 spheroidal state of liquids, is plainly attributable to the steam 

 being enabled to escape from beneath the fluid without rising 

 upwards through the mass ; and the rounded form which the 

 liquid assumes is simply owing to there being no adhesion 

 between the fluid and the dish to prevent the particles from 

 obeying the influence of their mutual attraction. 



With regard to the fact that liquids in the spheroidal state 



