37 



Now it is certainly very remarkable tluit this cori-ectioii is of the 

 same sign and the same order of magnitude as the planetai-y preces- 

 sion derived from the attraction of Skeligkk's ellipsoids. It must however 

 be kept in mind that it is very well possible to explain the discre- 

 pancy between the determinations of the constant of precession from 

 right-ascensions and from declinations (or from ni and from n) by 

 the hypothesis of systematic proper motions of the stars. Thus Hough 

 and H.\LM (M. N. Vol. LXX page 586) have from the hypothesis of 

 unequal distribution of the stars over the two streams derived a 

 systematic difference which is equivalent (for Nrwcomb)^) to a correction 



A./ = + 0".56. 



As the effect of the attraction of Seeliger's ellipsoids on the motion 

 of the moon Mr. Woi.tjer finds a secular motion of both the perigee 

 and the node. Both of these are due chiefly to the inner ellipsoid 

 and are thus not much altered if Seeliger's hypothesis is replaced 

 by either of the hypotheses .4 or C. We find 



Seeliger — = + 2".ll -4^ = — 2".50 



dt dt 



A -f 2 .04 - 3 .30 



C + 2 10 — 2 .06 



All these quantities are well within the limits of uncertainty of 



the observed values. 



Chemistry. — ''The application of the theory of allotropy to electro- 

 motive equilibria." II. By Dr. A. Smits and Dr. A. H. W. Aten. 

 (A preliminary communication). (Communicated by Prof. J. D. 



VAN DER Waals). 



(Communicated in tlie meeting of April 24, 1914). 



1. In the first communication ^) under the above title it has been 

 demonstrated that the theory of allotropy applied to the electromotive 

 equilibrium between metal and electrolyte, teaches that a metal that 

 exhibits the phenomenon of allotropy and is therefore built up of 

 different kinds of molecules immersed in an electrolyte, will emit 

 different kind of ions. 



The different kinds of ions assumed by the theory of allotropy, 

 need not be per se different in size, as was remarked before. They 



^) For Struve'ï; stars the correction would lie + U''.77. For Boss the corre- 

 sponding compHlation has of course not been executed by HouGH and Halm. 

 2) These Proc. Dec. 27, 1913, XVI. p. 699. 



