Proceedings of the Royal Irish Academy. 



Fig. 1. 



is made to stand up in a beaker, by suitably forming its end iato 

 a base (fig. 1). Tbe upper end of the strip is bent over and 

 touches tbe interior of another vessel. 

 'The liquid is placed in the beaker and 

 creeps over, and is collected in the 

 second vessel. The phenomenon di- 

 vides itself naturally into two parts : 

 (1) The initial stage, while the liquid 

 is forming a layer over the surface of 

 the strips ; and (2) when the con- 

 tinuous transport of liquid across to 

 the second vessel takes place. Passing 

 by for the present the initial stage, it 

 will abundantly appear from what 

 follows that a mixture is necessary for 

 continuous creeping. 



Though many attempts were made, no pure liquid could be found 

 which would creep. Yarious mixtm-es, however, were found which 

 did so actively. For instance, a pure paraffin (or rather what was 

 sold as such) did not creep, but the addition of a small quantity of a 

 lighter paraffin enabled it to do so actively. Again, ordinary paraffin, 

 which is, as is well known, a mixture of a number of different mem- 

 bers of the paraffin series, when left in the open air, loses much of its 

 lighter constituents and at the same time it is found to lose its power 

 of creeping in a like proportion. The power of creeping may be 

 restored by the addition now of a small quantity of a lighter oil. 

 Thus a liquid which has once crept over will not creep again nearly 

 so actively, if at all. If the surface-tension of the portion of liquid 

 which has crept over and been collected in the expeiiment described 

 above be determined, it will be found to be always greater than that 

 of the original liquid, and it also naturally consists of the less 

 volatile constituents of the mixture. This suggests that evaporation, 

 in conjunction with change in surface tension, plays an important 

 role in the phenomenon of creeping. This is easily verified by 

 covering the whole arrangement with a bell-jar. Evaporation being 

 thus prevented, creeping ceases likewise. 



"We now can see where the energy comes from to enable liquid, as 

 shown in fig. 1, to be continuously elevated and carried into the upper 

 vessel. Evaporation of the liquid lowers the temperature, and in 

 consequence energy can be obtained from the environments. The effect 

 is brought about, it must be observed, through the loss into the 



