( 189 ) 



investigation, mul of winch tlie tlieory of van der \Vaa],s could 

 give a closer desci-iption. 



The peculiai'ity of the examined system, which lies in the fact 

 that the vapour pressure of the one substance (ether) far exceeds 

 that of the other (anthraquinone), caused some wholly unexpected 

 ])henomena, and made it on the other hand jiossible to realize retro- 

 grade solidification on a much largei' scale than had been thought 

 possible till now. 



Laboratory for Anorganic Chemistry of the University. 



Amsterdam, June 1904. 



Chemistry. — "77ie preparation of silicon and its chloride.'^ Hy 



Prof. A. F. HOLLEMAN. 



(Communicated in the meeting of June 24, 1904). 



The numerous proposals which have been made for the prepara- 

 tion of the element silicon in both the amorphous and crystallised 

 form prove that a simple method has not as yet been found. W. 

 Hempel and von Haasy ^) have published in 1899 an additional 

 process consisting in the decomposition of silicon fluoride with sodium. 

 They melt this metal in small portions at a time in an iron 

 apparatns and then pass over the mass a current of silicon fluoride, 

 \vhich is then very readily decomposed. The brown porous mass, 

 which has been brought to a faint red heat is allowed to cool for 

 two or three hours in the current of silicon fluoride. An attempt to 

 convert it into silicoji chloride by heating the mass without previous 

 purification in a current of chlorine was unsuccessful. It was 

 impossible to remov^e the Na Fl and Na^SiFl^ b}' boiling with water ; 

 so in order to obtain pure silicon it was necessary to fuse the mass 

 with sodium and aluminium. The latter dissolves the silicon which 

 is then left insoluble on treating the I'ogulus willi (liliilc liydi'o- 

 chloric acid. 



Mr. H. J. Sr,i.(i'Eii who has repeated these experiments in my 

 laboratory showed (1) that by a small modification of the process 

 the crude product may be purified to such an extent l)y boiling 

 with water that it may be used for preparing silicon chloride ; 

 (2) the reason why the crude product on being treated with chlorine 

 does not yiehl silicon chloride. 



1. It is known that sodium fluoride readilv absort)s Si FL and 



') Zeilschr. f. aiioi-o-. Cli. 23, 3^. 



13* 



