92 KANSAS ACADEMY OF SCIENCE. 



The experiments to be described here consisted of attempts to fulfil these conditions, 

 and thus to compel the substance in changing state to follow the continuous instead of 

 the broken curve. 



II. 



By the simple method described to the Academy of Science at its last meeting,* I 

 have found it easy to prevent water in newly-blown bulbs from boiling until 130° was 

 readied, at which temperature, as in Donny's experiment, it invariably boiled explo- 

 sively. Sulphuric ether and bisulphide of carbon in such bulbs frequently attained a 

 temperature of 80° or 90° before boiling, and then burst explosively into gaseous form. 

 Above the normal boiling point, the expansion of the liquid was very rapid, but I have 

 not as yet succeeded in measuring it. The liquid in these experiments was separated 

 from the outer air by a short column of mercury, and when the change of state occurred, 

 this mercury was driven forcibly from the tube, together with the entire contents of the 

 bull). 



Upon placing a bulb filled with ether in a paraffine bath at 200°, the bead of mer- 

 cury being omitted, I found to my surprise that the ether, as in former trials, refused to 

 boil, and that although exposed to a temperature vastly above its boiling point, it re- 

 mained perfectly quiescent, going over into the gaseous state without ebullition. That 

 the liquid was superheated, was shown by its rapid expansion, but this expansion was 

 followed by a diminution of volume, which continued until the liquid had all disap- 

 peared. Inspection showed that the ether, during this process of contraction, was in the 

 spheroidal state. From previous well-known experiments upon the spheroidal state, we 

 know that the temperature of the liquid is always considerably below the boiling point. 

 In this case the transfer from the liquid to the gaseous state occurred under conditions 

 such that the expansion-curve was a continuous one. The general rorni was evidently 

 that predicted by Thomson — in the paper already cited — the temperature and volume 

 increasing to the point C (fig. 1), several degrees above the boiling point, when the 

 liquid, without boiling, assumed spheroidal form, and the temperature fell to a mini- 

 mum at E, considerably below the boiling point. 



The experiment as above described was repeated many times, and always with the 

 same result. It succeeded equally well where bisulphide of carbon was used instead of 

 ether, and would probably succeed in case of water in a bath of temperature sufficient to 

 throw that liquid into spheroidal form. Several attempts to repeat this experiment 

 with a thermometer immersed in the liquid failed. Nuclei of occluded gases, upon the 

 bulb of the thermometer, which no amount of cleansing with acids or caustic alkali en- 

 tirely removed, invariably induced boiling of the liquid as soon as it was placed in the 

 paraffine bath. Probably the only method by which the temperature of the liquid during 

 the entire experiment could be determined, would be by the use of a newly blown and 

 consequently perfectly clean thermometer. I hope, by means of an air thermometer of 

 proper form, to succeed in measuring these temperatures and also the accompanying 

 changes of volume. 



The conditions under which liquids may be converted into vapor without presenting 

 the usual broken expansion-curve may be briefly stated as follows: 



1. The liquid must be free from absorbed gases, and it must be heated in a vessel 

 upon the inner surface of which no gases are occluded. 



'2. It must be subjected to a temperature sufficient to produce the spheroidal state 

 without ebullition. 



3. It must have a free surface in contact with the air. 



A < lass-room Experiment on Superheated Liquids: Proceedings of the Kansas Academy of Science, 

 1883. [This method consists Of removing the air from water by repeated boiling in a small and newly- 

 blown bulb with a narrow neck, after which it is separated from the atmosphere by a bead of mercury. 

 I pon beating again, ebullition is invariably delayed until, at about 130°, the entire contents of the 

 bulb is expelled by explosive boiling.] 



