C. GENEEAL PHYSICS. 125 



torsion, but temporary magnetism increases by detorsion. 

 These effects can be explained by the same relation above 

 found between density and the magnetic force of iron. The 

 torsion increases the density of the iron, and the magnetism 

 must therefore diminish. By detorsion, the molecules of the 

 magnets are separated from each other, and the magnetism 

 itself increases. It can, then, be assumed as probable that 

 the magnetic forces in general are functions of the spaces 

 between the molecules, and dependent upon the dimensions 

 of these spaces. 19 (7, VIII., 151. 



RELATIONS BETWEEN CHEMISTEY AND THEEMOTICS. 



The study of the evolution of heat in chemical combina- 

 tions is a new branch of science, belonging partly to physics 

 and partly to chemistry, and the number of facts already 

 observed is sufficiently numerous to indicate certain laws 

 which are set forth by Berthelot. He premises that in the 

 act of producing any chemical change, the molecules hit 

 sharply against one another, and give off heat, just as when 

 a hammer strikes a bar of iron. From the study of the re- 

 lations between the amount of heat and the amount of work 

 done, it is possible to establish some theorems of thermo- 

 chemistry. 12 A, X., 473. 



RELATIONS OF HEAT AND ELECTRICITY. 



In a very suggestive article of Kohlrausch on thermo- 

 electricity, he develops the hypothesis that currents of heat 

 and of electricity are connected together in every conductor 

 of heat, the heat being moved by an electric current whose 

 heat-moving force is proportional to the electro-motive force 

 of the heat current in the same body. 12 ^1,X., 278. 



CONTINUITY OF THE LIQUID AND GASEOUS STATES OF 



MATTER. 



Professor Andrews, of Belfast, at the meeting of the British 

 Association in 1874, made a further communication on the 

 continuity of the liquid and gaseous states of matter. As 

 the result of some of his more recent investigations, he stated 

 that the compressibility of sulphurous liquids, unlike that of 

 water, diminishes as the pressure increases. A mixture of 

 three volumes of carbonic acid and four of nitrogen was sub- 



