( :^55 ) 



to ;i retarding action; which might then perliaps be explained in that 

 sense, that it is really the {CC/3CO . 0')-ion, previonsly coinl)ined 

 with the Fe---ion in some very definite manner, and split off tVom this, 

 which is resolved. All this is still problematical. One should rather 

 feel inclined to pnt this photochemical reaction (piilc on a level with 

 that of ferric oxalate : 



and : 



Fe, {C 6Y3 . CO,), ^ 2 F^ {C 67, . CO,), + 2 CO, + C; CI„ 

 or if we assume a splitting of ions; 



and : 



2 Fe- + 2 {C 6V, CO . O)' -^ 2 Fe- + 2 CO^ + 6', CI,. 

 It is, however, still the cpiestion whether this conclusion is ftdh 

 justified and whether it is not probable that several more intermediary 

 stages occur; tliis will have to be elucidated by further research. 



§ 12. Finally we nia\ mention a few experiments with solutions 

 of ferric-pentachloropropionate, of which a sensitiveness to light was 

 fully to be expected on account of the experience, gained during this 

 investigation. 



The acid for this |)urpose was handed over to me by my colleague 

 BoF:sEKEN to whom I again bring my thanks. The melting-point is 

 situated between 210° and 215°; the chlorine-content, according to 

 B.'s statement has been found as 72.()57„— 71.78"/,, ; theory: 727,,. 



The preparation of the Ba-salt by neutralisation at the temperature 

 of the room, presented difficulties in so far that a sweet smelling oil 

 separated even in the dark. Nevertheless, the neutralised solution was 

 precipitated with the calculated ({uantity of ferric sulphate and by 

 repeatedly filtering in the dark and in the cold a clear greenish-yellow 

 solution was obtained. This is very sensitive to light and gets very 

 soon (lecom|)Osed into CO^ and a heavy colourless oil with formation 

 of large quantities of Cl'-ion in the solution. The oil was sepai-ated, 

 j)uritied and dried and identified as (/2CI4. The photochemical splitting 

 of ferric-|)entachlor()[)r()pi(»nate is therefore perhaps represented by: 



/(X),.CCl.,.CCb, /'CO,.CCI,.CCM,. 



Ke— C0.,.CC1.,.CCI, -^CO, + C,C\, + Fe— CO,.CCI,.CCI,. 



\(:.o.,.cci3.cci, \ci 



etc., 

 iHitil, probably, FeClj alone finally remains; the colour oftheli(pnd 

 is brownish yellow. 



