70 Intelligence and Miscellaneous Articles. 



apparatus is discharged, every thing returns to the initial state : 

 the liquid which had descended in the tube of the inner vessel rises 

 again ; and that which had risen in the tube of the outer case re- 

 descends. We must therefore conclude that the internal capacity 

 and the external volume increase during the charge of a Leyden jar. 

 To leave no doubt on the subject, I will review the objections 

 which can be made to this conclusion. 



(1) The effect cannot be attributed to a rise of temperature, 

 since the discharge causes it to disappear immediately instead of 

 increasing it. 



(2) Electric pressure might be suggested as the cause; but that 

 would be the same on both faces of the dielectric, and then it would 

 produce a diminution of volume instead of the increase observed. 



(3) It might also be said that the liquid does not perfectly wet 

 the glass before the electrization, and that afterwards, in conse- 

 quence of attraction, more intimate contact is produced, giving rise 

 to an apparent contraction of the liquid. But then the same phe- 

 nomenon ought to be produced for the exterior liquid — which does 

 not take place. 



(4) Again, different properties of the positive and negative ar- 

 matures might be mentioned. But if the communications of the 

 apparatus with the electrical machine be reversed, the direction of 

 the phenomenon does not change. 



In short, it is established that, in a Leyden jar, the insulator un- 

 dergoes, through the electrization, a dilatation which can neither be 

 accounted for by a rise of temperature nor by an electric pressure. 

 We therefore find ourselves in the presence of a new phenomenon; 

 as to the interpretation that may be given of it, although several 

 present themselves to the mind, it would be premature to discuss 

 them. 



M. Jainin, in presenting the above Note to the Academy, was 

 anxious to acknowledge that, ten years since, M. G-ovi had made, and 

 published in the Actes de VAcademie de Turin, the first part of the 

 experiments of M. Duter. M. Grovi observed that the internal volume 

 seems to increase during the charging of a Leyden jar; and he 

 attributed this effect to a contraction of the liquid which it con- 

 tains ; but he did not institute any experiment to show that the 

 external volume is augmented. This is what M. Duter has done ; and 

 it has led him to a conclusion contrary to that of M. Govi — namely, 

 that the effect observed is simply due to a dilatation of the dielec- 

 tric case. — Comptes Rendus de VAcademie des Sciences, Nov. 23, 

 1878, tome lxxxvii. pp. 828-830. 



NEW OBSERVATIONS ON THE PART PLAYED BY PRESSURE IN 

 CHEMICAL PHENOMENA. BY M. BERTHELOT. 



Permit me to call attention to a circumstance in the remarkable 

 experiments of M. Pictet on the liquefaction of oxygen and hydro- 

 gen. Perhaps it will not be uninteresting to remark that the 



