1005 



It niav 1)0 readily coikUmisimI to a (•oloiii'Uvss, very nioltilc li(|iii(l 

 wliit'h solidifies below — 50°. 



Liquid diehloroacetylene rapidly eoirihincs at — 50° with eldorine 

 tot C,C1,, 



The gaseous eompouiul, at least if diluted with H.^ or CO^, does 

 not seem to be dangerous, but the liquid substance explodes with 

 extreme violence. 



Delfi, 12 March 1914. 



Chemistry. — "On (he Isotnorphi/ of the hjthyUu.lphates of the }fet(ils 

 of the Rare Earths, and on the prohkni of eventual niorpho- 

 tropic relations of these salts loith analogous salts of Scundian}, 

 Indium and BerijlUwn." By Prof. P. M. Jaeger. (Communi- 

 cated by Prof. P. VAN Rombukgh.) 



(Communicated in the meeting of March 28, li)14). 



§ 1. In the following paper is given a short review of a comparative 

 study of crystallographical analogies within the series of the Ethyl- 

 sulphates of the metals: Yttrinni, Lanthanium, Cerium, Praseodyniiun:, 

 Neodymium, Samarium, Europium, GadoUnium, Dysprosium, Thu- 

 lium, Erbium, Neoytterhimn, Beryllium, Scandium, SiU(\ f ndium ; and 

 also of some Acetylacetonates of the three last metals. These investiga- 

 tions were all executed, during the last two years, by means of 

 very small quantities (about 100 to 300 m.G.) of the oxides, which 

 for this purpose were kindly lent to me in the possibly highest 

 degree of purity, by the scientists: Professor G. Urbain in Paris, 

 Sir William Crook ES in London, and Professor C. James in Durham. 

 New Hampshire (U. S. A.). It is an agreeable task to me to thank 

 the above mentioned chemists here once more for their kind hel]) 

 in this matter. The complete description of these investigations will 

 be given in a full paper, which I liope to publish elsewhere ') within 

 a short time, with all the data and necessary figures. 



§ 2. This research was started with respect to the question, 

 if it would be possible, to find out any relation between the changes 

 of the crystallographical parameters, which are caused by the sub- 

 stitution of the trivalent atom Me-- in the molecule: 



.M^r(SO, .C,H3)« + 18H,0, 

 by any other atom of the series of elements here considered, an<I 

 between the changes in molecular weight, which are simultaneously 

 produced by this substitution. That in general a parallelism of the 



1) In the : Recueil des Travaux d. Ghim. des Pays-Bas, (1914). 



