49 



than HoBSDN and Young did, by means of the following M proof of 

 theorem 3. which is valid for (he space of n dimensions: 



For each positive integer r we describe round each point q of Q 

 as centre with a radius smaller than f., (//;« 6, = 0) a sphere which, 

 if ^ is a point of the adherence Qci^a, excludes all points of the 

 derived set of Qc'\ In this way for each positive integer r a set of 

 regions ./, containing Q is determined. 



The inner limiting set J) (J.,) then possesses the properly required. 

 For, if j) be a limiting point of Q not belonging to Q and not being 

 a limiting point of the ultimate coherence of ^^, a traiisfinile number r^, 



exists with the property that/» is nol a limiting point of ^2'' ''• ''nt l'»' 

 any « <^ t^, is a limiting point of Qc. Then on one hand p is 

 excluded by every sphere described round a point of .5" Qca, on 



the other hand a positive integer o^, exists so that /> is excluded by 



every sphere described for a i' ^ (j^, lound a point of Qc'i'. Hence 

 p lies outside every ./., for which r > <t^,. so that // cannot belong- 

 to 2) (J;). Thus the theorem has been established. 



Chemistry. — •'furcitii/d/ions on Pastk.uk'.v Principle of the Rela- 

 tion /letireeit Moleciilir uiul Plnjsical Dlssi/Dinietn/." II. By 

 Prof. Dr. F. M. JAK/iKu. (Communicated by Prof. H. Hag.\). 



(Communicated in tlie meeting of April 23, 1915). 



§ 1. In the following are reviewed the results of the crystallo- 

 graphical investigations upon which the conclusions explained in the 

 previous paper") are founded. 



I. Racemlc Luteo- Triethi/lenedinmlne-Cobnltihromlde. 

 Formula: \Co (Aein),\ Bt\ + 3 ///>. 



This compound was prepared by two methods: 1. Starting from 

 praseo-ilietkyli'iiediamine-dichloro-cohnltichlorlde: \Co [Aeln)„ Cl^\ CI, by 

 heating with ethylenediamine and precipitating with a concentrated 

 solution of sodiumbromide ; 2. By heating purpureo-pentamlne- 



1) This proof was communicated aliout two years ago to Schoenflies, who 

 on p. 856 of his Enlwickelung der Mengenlehre I, applies it to prove the follow- 

 ing special case of llieorem 2 : 'Ereri/ component of a couutabte closed set is 

 an inner limiting set". Comp. Hobson, i.e. p. 320: "Every reducible set is an 

 inner limiting set". 



-) Vid Tiiese Proceedings, Maicli 1915. 



4 



Proceedings Royal Acad. Arasterdanir Vol. XVIII. 



