80 Intelligence and Miscellaneous Articles, 



system of atoms in equilibrium of temperature, we have 



«*=/W. (3) 



a being a specific coefficient, and /(r) a function of the absolute 

 temperature, which is the same for all the atoms or systems of 

 atoms. 



Lastly, from the value, ascertained by experiment, of the vis viva 

 of the centre of gravity of the molecule of any perfect gas, I deduce 

 that a is the same for all the atoms or atom-systems, and that 

 equation (3) may be put in the form 



(f) = ar, 

 a being a constant which plays, in regard to the temperature, a 

 part analogous to that of the mechanical equivalent in regard to the 

 calorie. 



This is, with one more degree of generality, the consequence 

 which I deduced from Carnot's theorem, which is thus, I think, 

 for the first time rationally demonstrated. 



Ampere, in a remarkable note inserted (in 1833) in vol. lvhi. of 

 the Annates de Ghimie et cle Physique, had indicated some ideas ana- 

 logous to those I have developed in my memoir. 



In another paper I shall point out some of the most important 

 consequences which may be deduced from my theory. I shall par- 

 ticularly dwell on those which have drawn upon the theory of the 

 atomic volumes of bodies — a theory of great importance for che- 

 mistry and mineralogy, and the study of which was the starting- 

 point of my researches in thermodynamics. — Comptes Rendus de 

 VAcad. des Sciences, vol. lxxv. pp. 1479-1482. 



ON ELECTROMAGNETISM. BY M. TREVE. 



It is known that steel needles can be magnetized by discharges 

 from a Ley den jar passing through a wire running round them ; 

 consequently static electricity has in this case the same properties 

 as dynamic currents. This property belongs also to Buhnikorff's 

 induction-coil when its currents are caused to pass in & glass solenoid 

 containing a rarefied gas. 



I placed in the axis of the solenoid some bars of steel, which a 

 single discharge was sufficient, to transform into magnets. This 

 was a thing foreseen. But though this experiment establishes no 

 new fact, it is perhaps of a kind to make comprehensible the pheno- 

 menon by means of which Ampere completed his theory of terres- 

 trial magnetism. Indeed, suppose we make the glass solenoid big 

 enough to envelop the earth, and cause currents from an induction- 

 machine to pass through it, we shall magnetize every thing mag- 

 netic found there, and all needles will be deflected in proportions 

 variable with the intensity of the current. 



I think we have here a tolerably correct picture of the electrified 

 gaseous currents which, according to Ampere, incessantly circulate 

 round our globe from east to west, forming as it were an immense 

 coil that acts on the variable horizontal and vertical currents. — 

 Comptes Rendus de VAcad. des Sciences, vol. lxxv. p. 1624. 



