Intelligence and Miscellaneous Articles, 77 



If the magnet has its extremities free, it is ascertained that the 

 free magnetism increases gradually from the neutral line to the ex- 

 tremities. The curve of the intensities is very near that indicated 

 by Coulomb. When a contact is applied, all is changed : two poles 

 make their appearance at the two extremities of the contact ; the 

 free magnetism of the magnet partially disappears ; it augments 

 with the distance to a maximum, to decrease afterwards towards 

 the middle line of the magnet. The conditions of these modifications 

 are very complicated, and merit a very close study. They contri- 

 bute to the production of the changes of direction of the needle 

 examined by M. Treve ; but in no case can these changes reveal 

 the distribution of the magnetism in the bar, and they cannot be 

 summed up by saying that the poles of the magnet have changed 

 their position. — Comptes Mendus de TAcademie des Sciences, vol. lxxv. 

 pp. 1572, 1573. 



RELATION BETWEEN THE PRESSURE AND THE VOLUME OF SATU- 

 RATED AQUEOUS VAPOUR WHICH EXPANDS TN PRODUCING 

 WORK WITH NEITHER ADDITION NOR SUBTRACTION OF HEAT. 

 BY H. RESAL. 



Let Y, p, p, r be the volume, pressure, density, and heat of vola- 

 tilization of saturated aqueous vapour at t , and c the specific heat 

 of water at the same temperature. Admitting that the suffix re- 

 fers to a determined weight of saturated dry vapour, and the suffix 

 1 to the vapour not condensed during the expansion, we have, on 

 properly transforming one of Clausius's equations : — 



L = 273+J, P J_r^ VK 273+ IA 



T r, P A273+* 2 _ g 273 + *„; 



I have considered some values of t , successively decreasing by 

 10 degrees, from 200 to 110 ; for each of them I diminished t v 10 

 degrees, commencing at t — 10. I was thus able to form Tables 



giving values of — i, opposite to which I placed the corresponding 



values of -O ; and I found that the relation 

 Pi 



P 1 W 



very satisfactorily accords with the elements of those Tables, be- 

 tween the limits 1*25 and 15*37 of =?■. — Comptes Rendus deVAcad. 



* 



des Sciences, Dec. 2, 1872, p. 1475. 



ON THE DEFINITION OF TEMPERATURE IN THE MECHANICAL 

 THEORY OF HEAT, AND THE PHYSICAL INTERPRETATION OF 

 THE SECOND FUNDAMENTAL PRINCIPLE OF THAT THEORY. BY 

 E. MALLARD. 



The study of calorific phenomena has led to the introduction into 

 science of two quantities sui generis, the calorie and the temperature, 

 which every theory must necessarily define. 



