Intelligence and Miscellaneous Articles. 231 



193°. The two columns o£ mercury presented a greater or less 

 difference according to the initial difference. The equalization of 

 the mercury-levels took place at 196°. The formula expressing 

 the equilibrium of the two parts of the tube shows that the course 

 of the difference of level corresponds very appreciably to that of the 

 difference between the density of the liquid and that of the vapour. 

 The phenomenon of Cagniard de Latour was observed in seven 

 tubes, in which the volumes of the liquid and the vapour were, at 

 the temperature of 18 0, 6, respectively in the following ratios : — 



4 2 1^4^7 

 1 5 2 11 5 10 5* 

 From the results obtained the author concludes that, in order 

 that the meniscus can be observed in the tube, the ratio — of the 



volume of the liquid to the volume of the vapour at the ordinary 

 temperature must not be below a lower limit comprised between 



1 a 2 

 4 and V 



nor above a higher limit comprised between 



— and -. 

 10 5 



Comparative experiments on several tubes heated in the same 

 bath have shown that the temperature at which the meniscus dis- 

 appears is not constant for the same body, but depends on the 

 quantity of this body compared in a given volume. In the same 

 tube the reappearance was constantly observed at the same tem- 

 perature as the disappearance. — Journal de Physique, June 1893. 



THE CRITICAL POINT, AND THE PHENOMENON OF THE DISAP- 

 PEARANCE OF THE MENISCUS WHEN A LIQUID IS HEATED 

 UNDER CONSTANT VOLUME. BY G. ZAMBIASI. 



The fact established by the author in the above Note, that the 

 temperature U at which the meniscus disappears is not constant, 

 but rises when the ratio of the initial volume of the liquid to the 

 volume of the vapour disappears, might have been foreseen from 

 Jamin's experiments, in which the disappearance of the meniscus 

 was obtained by a compression at constant temperature. M. 

 Amagat has demonstrated the same fact in a still more accurate 

 manner in producing, by a slow increase of pressure of carbonic 

 acid, the disappearance at 30 o, 50, when heat alone produces dis- 

 appearance at 31°-55. If the temperature t c was singular, it would 

 be independent of the compression. 



It does not increase the tension, which is a maximum • but by 

 condensing the vapour it increases the volume and the mass of the 

 liquid, so that the ratio of the volumes increases. 



