June 25, 1891] 



NATURE 



'^75 



For any liquid, the absolute temperature T of the boiling 

 under a pressure of /> atmospheres is determined by the same 

 general law slightly specialized as follows : — 



T = Y, + Y, (4) 



where 



Yi = Ki[i-4 + log/] (5) 



and 



Y., :r KjLlogTT - log/]- (6) 



The logarithmic limits of all liquids intersect in the same 

 absolute zero point determined by T = o =: - 273° C. and 

 log/ = - I "4. For each individual liquid this limit extends 

 upwards to the critical point of the liquid, p ~ tt and T — Q. 

 For many liquids the critical point can be theoretically calcu- 

 lated, as well as the value of the parameter. It is understood 



Fig. 2. 



that the parabolic curve is tangent to the logarithmic limit at 

 the critical point. 



It hardly needs to be said that the tension of dissociation, and 

 even the solubility of solids, are subject to the same general law. 



The fusing points are obtained by simply changing the sign 

 in (i) to 



t ^y^ - y-i (7) 



so that the parabolic curve will be placed below the logarithmic 

 limit. 



One of the most remarkable results of this research is the 

 mechanical determination of the true position of the carbon 

 atoms in organic serials, and the cjmplcle explanation of the 

 difference in fusing point between compounds containing an 

 even and odd number of carbon atoms. 



It should also be understood that the change in fus>ng point 

 produced by change in pressure is expressed by the same general 

 law. 



Putting log a = x, log p = z, and log a = {, log tt = C, the 

 formulae (l) to (7) will become 



t^y^± y„ y, = ^,(x - i\ y., = /•.,({., - xy- , (8) 

 T = Y, + Y,. Y, = Ki(= - 0. Y, = K,[(, - zy . (9) 



These formulre strikingly show the simplicity of the laws 

 stated, and also determine the surfaces formed by the co- 

 ordinates X, t, and y in general. 



NO. I I 30, VOL, 44] 



In subsequent notes special topics covered by this general 

 law will be laken up, and the complete concordance of the law 

 with the results of observations will be shown. 



Porpoises in African Rivers, 



In reference to Mr. Sclater's letter in Nature of June u 

 (p. 124), the following may be interesting to your readers : — 



The skull of a Delphinoid Cetacean from Cameroon has 

 lately come into my hands, through the kindness of Prof. 

 Pechnel-Loesche. The sender, Mr. Edward Teusz, gave the 

 followin? information concerning it. The animal to which it 

 belonged was caught in Kriegschiff Bay, after very heavy rains, 

 and was being devoured by sharks. The contents of the stomach 

 consisted of grass, weeds, and mangrove fruits. None of the 

 natives had ever seen the animal before. In preparing the 

 skull, Mr. Edward Teusz noticed that the nostrils projected 

 above the surface of the forehead. 



I am preparing for publication a detailed description of the 

 skull, and must here confine myself to remarking that, though 

 the animal belongs to the genus Sotalia, it differs in several 

 essential points from all the species of that genus hitherto de- 

 scribed. I have no doubt that it is a new species. There are 

 twenty-seven teeth on each side in each jaw. Their form, in 

 that they are not pointed, but worn down, indicates, as also do 

 the contents of the stomach, that the animal is herbivorous. It 

 therefore seems certain that it is a fresh-water animal. It is 

 well known that other Sotalia live in rivers. 



Jena, June 20. Willy Kukenthal. 



PHYSICAL SCIENCE EOR ARTISTS} 

 I. 

 T THINK it right that I should begin by explaining how 

 ■•■ it is that I am liere to-day, to lecture to you on a 

 subject which touches art as well as science. It happens 

 in this wise. Some years ago, while studying a certain 

 branch of optics, it became important for me to try to 

 learn something of the exact sequence of colours at 

 sunrise and sunset ; and being, like you, busy all day in 

 a large city, I thought it would not be a bad idea, and 

 that it would save a little time, if I studied pictures repre- 

 senting these phenomena en attendant the happy holiday 

 time that I should spend in the country. So I went to 

 the Academy and other picture galleries, and endeavoured 

 to get up the information from pictures which I could 

 not at that time get from Nature herself. I then had, 

 as I have still, such an extreme respect for art and artists 

 that I was perfectly prepared to take the pictures as re- 

 presenting truthfully what I wanted to see. The result, 

 however, brought me face to face with a difificulty that I 

 was not long in finding out. I was driven to the conclusion 

 that artists could be divided into two distinct classes — • 

 those who studied Nature and Nature's laws, and gave us 

 most exquisite renderings of this or that, and those 

 who apparently considered themselves far superior to any 

 such confining conditions as would be imposed by any 

 law ; and that, unfortunately, made me a little doubtful as 

 to the results. 



My friend, and your friend, Dr. Russell, happens to 

 know this little bit of my experience, and hence it doubt- 

 less is that he requested me to come down to-day to say 

 a few words to you, his plea being that this College 

 is one of the very few institutions of its kind in the world 

 where there is a studio and a physical laboratory side 

 by side. 



That, then, is the reason I am here, and what I want 

 to impress upon you to-day is that the highest art can 

 only be produced by those who associate the stud\ of 

 physical science with the study of art, and that therefore 

 the possible producers of the highest art can only be 

 looked for in such an institution as this if training of 

 any kind has anything to do with it. 



' A Lecture delivered at Bedford Co'.lcg;, by J. yormnn Loc'^cyer, F.R.S. 

 on Jiin: 10, iSgi. 



