807 



tlie hori/.ontal vibrations (i.e.- of the ordinary waves), is at the 

 same time the direction of niaxinium lif>iit-ahsorp(ion. 



As the field A corresponds thus with that direction of vibration, 

 wherein the maximum absorption of the radiant energy talves place, 

 so the apparent temperature must also seem higher in that held, 

 — quite in accordance with the law of Kirch hoff. 



Groningen. Laboratory for Inorganic and 



Physical Chemistry of the University. 



Chemistry. — "Allotropy and electrooiotioe EqiuUbrium." By Prof. 

 Ernst Cohen. 



(Communicated in the meeting of January 31, 1914). 



In the address on allotropy which I delivered on May 16^'' 1904 

 at the opening of the van 't HoFF-Laboratory at Utrecht (this adress 

 has been published as a pamphlet and also in the "Cheraisch Weelc- 

 blad" ^)) I called the attention of my audience to the importance of 

 a systematic study of this phenomenon. I also gave an outline of 

 the way to be followed in continuing the researches I had carried 

 out with my collaborators in this direction since the year 189y. 



Since that time Mr. Smits at Amsterdam has also chosen allotropy 

 as a field of work. Into that matter I shall not enter further at 

 present. 



However attention may be called to the form which chamcterizes 

 Mr. A. Smits' publications and which may give rise to a misunder- 

 standing. 



This is strikingly shown in his paper in these Proceedings Vol. 16, 

 p. 708 (^meeting of Dec. 27, 1913) where he says: 



"In connection with the foi-egoing it is desirable to draw attention 

 to this that according to these considerations the contact with die 

 solution of a salt of the metal must have an accelerating injiuence 

 on the setting in of the internal equilibrium of the metal." 



Mr. A. Smits has written these words in italics; he has however 

 forgotten to mention in the text or in a footnote thai this fact was 

 discovered and published 15 years ago by Ernst Cohen and C. van 

 Eyk in their researches on the allotropy of tin *). 



Moreover he forgets to point out that an explanation of this 



^) Ghem. Weekbl. 1, 481 (1903/04). 



2) Zeitschr. f. physik. Ghem. 30, 601 (1899). 



52 



Proceedings Royal Acad. Amsterdam. Vol. XVI. 



