Thermal Relationship between Water and certain Salts. 123 



the water above the wire, in this it is obtained from the water 

 which is about the sides of the tube. The existence of the 

 tightly fitting cylinder of ice inside the tube, so far from being 

 an objection to this explanation, is a necessary consequence 

 of it. 



In order to confirm this explanation, PfafF's experiment 

 was repeated with four pieces of tubing — of glass, copper, 

 brass, and lead, each about 1 foot long and | inch bore. The 

 distances to which the tubes penetrated in four hours are 

 contained in the following table: — 



Tube. 



Load. 



Distance. 



Copper 



21b. 

 2 „ 

 2 „ 

 2*„ 



100 millim. 

 35 „ 

 7 „ 

 3 „ 



Brass 



Lead 



Glass 





The glass tube was loaded with an extra half-pound in order 

 to make up for its smaller weight. 



This shows conclusively that when the experiment is made 

 at a temperature not lower than 0° C, the chief factor is the 

 lowering of the freezing-point by pressure, and not the plas- 

 ticity of ice. But in the same paper PfafF describes experi- 

 ments conducted at temperatures below zero in which the iron 

 tube still penetrated into the ice, though to a very much 

 smaller distance than before. Thus, at a temperature varying 

 from —4° to —1°, the same tube which at 0° sank 30 millim. 

 in one hour, sank only 1| millim. in twelve hours. In this case 

 the experiment seems capable of explanation only by admitting 

 the presence of a certain degree of plasticity in ice, which is 

 rendered very probable by other experiments described by 

 PfafF, where a sheet of ice bends gradually under its own 

 weight. 



XIV. On the Thermal Relationship between Water and certain 

 Salts. By B. Illingwoeth and A. Howard*. 



THE study of the relationship towards water of certain 

 organic salts belonging to one and the same series promised 

 to throw light upon the general question of the relationship 

 between salts and water, inasmuch as the degree of difference 

 between the members compared may be made at will very 



* Communicated by the Physical Society. Read June 14, 1884. 



