1003 



at the tcin|)oratiii'c of llio room and was cooled ii) a mixtm-e ol'solid 

 carbon dioxide and alcohol it gave the following resnlts: m.p. z=: — ^10°, 5 ; 

 di''-> = 0.740; n'-^-^^zzi 1.5172; MR,) =32.7. 



4 ' D ) w 



After standing for a week over potassinm iiydroxide this liquid 

 was again distilled at the ordinary pressure. Now was found : 

 ni.p. —11° to— 10°; d'; = 0.7396; !);;»■-= 1.5167; Mlli) = 32.7. 



BVoni this we notice that the distillation at the ordiuarj' pressure 

 exerts no influence on the properties of the hydrocarbon so that the 

 above-cited constants may be really taken to be those of pure 

 hexatriene. The results mentioned here biiefly, will be communicated 

 more fully elsewhere. 



Utrecht. On/. Cltem. Lab. University. 



Chemistry. — "On dichloroaceti/Iene'. (A warning). By Prof. J. 

 BöESEKKN and J. F. Carrière. (Communicated by Prof. A. F. 

 Holleman). 



(Communicated in the meeting of March 28, 1911). 



Our object was to prepare di-trichlorovinylketone from thrichloro- 

 acrylic acid by elimination of carbon dioxide and w^ater. 



It was, therefore, tirst attempted to efl'ect this decomposition by 

 a careful dry distillation of the barium salt : 



(CCl, : CCl.COO), Ba = Ba CO3 + (CCI, : CCl), CO. 



In a provisional investigation it appeared however, that a strong 

 charring took place, whilst the barium was left in the form of chloride. 



When the experiment was repeated much carbon dioxide was 

 evolved and further a gas with a disgustingly sweet odour, which 

 formed a strong nebula in contact with the air. 



This nebula formation was coupled with a decided chemo-lumini- 

 ferous phenomenon, so that wc sus[)ected that the most simple carbon 

 chloride dichhroacetylene had formed according to the equation. 

 (CCL, : CCl.COO), Ba = BaCI., H-2C0, + 2 C.Cl^ 



As we had to take into account the possibility of dealing with a 

 very explosive compound, a (piantity of only one gram of the barium 

 salt was slowly heated in a di-y current of hydrogen. After first 

 passing the gases through an empty suction tube, in wdiich a fairly 

 large quantity of bye-product (with high b.p.) was retained, they 

 passed through a similar tube placed in a Dewar vessel in which 

 the temperature was brought to — 70*^. 



In this remained a little of a colourless, solid substance which 

 melted below — 50° to a mobile, colourless drop of liquid. 



