( 530 ) 



A second test was obtained from an investigation of the .1 stars, 

 made for another purpose some time ago. In this investigation the 

 materials for each region of the sky, were divided in tw^o approxi- 

 mately equal parts, the one containing the greater proper motions, 

 the other the smaller. In no case however, proper motions exceeding 

 0"06 were admitted in the latter group. Yet tiiis group still shows 

 the two streams with perfect clearness. 



Tt would seem to me, that the conclusion towards which these 

 results lead, is decisive. 



The two star-stream-system is not confined to the nearest neigh- 

 bourhood of the sun, but it extends at least to those parts of space 

 which contain 40 procent of the observed helium-stars. We therefore 

 need an explanation for the exceptional behaviour of the helium 

 stars, different from that oi' Eddington. 



In Halm's theory the third stream is not confined to the more 

 distant parts of space. Oui- theory differs from his in so far that it 

 does not lead us to distinguish three sharply defined streams, but to 

 conceive tiro stream-systems each consisting of a series of streams, 

 gradually merging into each other. Halm's third stream is one of 

 the extreme cases of our first stream-system. 



In an extensive investigation of the helium- and early A-stars, 

 undertaken by Adams, Babcock and myself, we intend to collect 

 and discuss the materials necessary for a fully satisfactory determina- 

 tion of the elements of the two streams. 



The present paper is to be considered as part of that joint labour. 



Chemistry. — "The .system Iron-Carbon'\ By Prof. A. Smits. 

 (Communicated by Prof. A. F. Holleman). 



After Bakhuis Roozeboom ^), led hy his theory of mixed crystals, 

 had set forth his view about the system iron-carbon, attention has 

 been drawn by various scientists to the fact that though Bakhuis 

 Roozeboom's considerations have contributed considerably to get a 

 better insight into this so important system, his views are in opposition 

 to practice in a single significant point. 



Bakhuis Roozeboom had namely thought he was justified in con- 

 cluding chiefly from experiments of Roberts Austen, that the mixtures 

 with more than 2 7o C. must be subjected to a radical change in the 

 neighbourhood of 1000' with stable equilibrium. 



Roberts Austen had namely found that the line indicating the 



^) Zeitschr. f. physik. dhem. 34, 437 (1900). 



