152 Intelligence and Miscellaneous Articles, 



districts. He discusses the evidence furnished by the igneous rocks, 

 and points out the abnormal position both for the British and Ger- 

 man areas which these would occupy, if the breccias were of Triassic 

 age. 



XV. Intelligence and Miscellaneous Articles. 



ON THE CONCORDANCE OF ORTHOBARIC CURVES FOR SOLUTIONS 

 AND HOMOGENEOUS LIQUIDS. BY L. NATANSON. 



TDE.OP. Orme Masson, pursuing the line of inquiry started by 

 -*• M. van't Hoff with such success, has been able to point out a 

 remarkable analogy between the systems formed by a liquid and a 

 saturated vapour, with certain solutions partially soluble in each 

 other. In order to put this analogy in its simplest form, let us 

 assume that vapours are solutions of matter in a vacuum, and 

 liquids solutions of vacuum in matter ; the case of two mutual 

 solutions in equilibrium will then become the general case, which 

 will comprise, as a particular case, the ordinary equilibrium of a 

 liquid in the presence of a saturated vapour. 



From this point of view the author inquires whether it is not 

 possible to transfer to solutions the well-known propositions of 

 van derAVaals on the fundamental relations which apply to various 

 bodies in the state of saturated vapour. For this purpose he has 

 constructed five "orthobaric lines," to use the expression of Eamsay 

 and Young — that is to say, curves which show the relation of the 

 volumes of the liquid and of the vapour with the temperature, 

 even at the limits of saturation. The five combinations of liquids 

 which have been chosen are those whose solubility has been inves- 

 tigated by M. Alexejeff, and the thermal expansion of which may 

 be considered as known. These five combinations are as follows : — 

 aniline and water, aniline and sulphur, isobutylic alcohol and water, 

 phenol and water, essence of mustard and water. The considera- 

 tion of these curves gave the values of the critical elements, that 

 is to say the temperature and the volume of unit mass at the 

 critical point of the solution. These values were then adopted as 

 new units ; and it was found that orthobaric curves referred to the 

 respective critical elements agree with each other, the differences 

 peculiar to them having disappeared. To this result another is 

 attached. The orthobaric curve, which is unique for different 

 solutions, is the same as that which applies to homogeneous bodies. 

 This conclusion is corroborated by the calculation of orthobaric 

 curves for ether, from Eamsay and Young and M. Battelli ; for 

 methylic alcohol and ethylic alcohol, from Ramsay and Young ; lastly 

 for carbonic acid and nitrogen protoxide, from MM. Cailletet and 

 Mathias ; as well as by the detailed comparison of all those curves 

 with those which have been calculated for solutions. — Bulletin de 

 VAcademie des Sciences de Cracovie, June 1891. (Communicated by 

 the Author.) 



