VI 1 



had shown that the law of corresponding temperatures that Groshans 

 modified from Dalton involved the law that at any given pressure the 

 latent heat of vaporisation per unit volume of many substances was 

 the same. After Van dcr Waals' memorable paper on the continuity 

 of the liquid and gaseous states, Clausius published an elaborate 

 investigation of this subject, in which he developed the application of 

 a rather complicated formula, and showed that it represented the 

 experiments throughout an enormous range with wonderful accuracy. 

 There is a measurable departure from the law in calculating the com- 

 pressibility of the liquids. To facilitate the application of this 

 formula, Clausius invented and calculated the values of a special 

 transcendental. 



Electricity and magnetism attracted Clansius' attention from time 

 to time, at first in connexion with heat and molecular physics, and 

 afterwards with reference to the theory of electrokinetic actions. In 

 1858 he developed the theory that the molecules in electrolytes are 

 continually interchanging atoms, and that the effect of electric force is 

 to direct the interchange and not to cause it. It seems, however, 

 possible that as synchronous systems near the solar system might 

 break it up, while asynchronous ones might not, so a polarisation 

 of the atomic motions in a liquid might result in a proportionate 

 breaking up of the molecules which before this introduced regularity 

 were stable. In reply to Hittorff's objection that gases should obey 

 Ohm's law, Clausins answered that there were too few molecules. 

 This can hardly be considered conclusive in presence of electrolytic 

 conduction in very dilute aqueous solutions. His theory, however, 

 explains almost all the known facts of electrolysis, and has been 

 extended by others to explain many other phenomena with most 

 remarkable success. He investigated electric osmosis, and hints that 

 it is produced by electric forces due to charges over the surfaces of 

 the pores in the diaphragm. He remarked that the resistance of 

 pure metals is proportional to their absolute temperature. 



His electrokinetic theory, founded on a theory of action at a 

 distance between electrical elements moving in conductors, led to the 

 conclusion that the action between the elements must depend on 

 their absolute velocity and not on their relative velocity. This prac- 

 tically postulates a medium with reference to which the elements 

 move, and by which the actions are propagated. 



With the great development of electrodynamics as a machine for 

 applying energy to do man's work, Clausius repeated his exploration 

 of the theory of the steam engine, that great machine for applying 

 heat energy to do work, dnd investigated on broad principles the 

 theory of dynamos. Some of his work in this direction is super- 

 seded by the rapid development of the science and its applications, 

 but his insight into the problem is evidenced by his having been one 



c 



