150 



Royal Society :- 



out theoretical interest. The molecule of dibromide of ethylene, 

 equivalent to 2 molecules of hydrobromic acid, fixes in this reacticu 

 2 molecules of triethylphosphine, equivalent to 2 molecules of am- 

 monia, the result being a compound saline molecule, equivalent to 2 

 molecules of sal-ammoniac. 



(C,H,)./ 



(C.H,), 



(C,H.)". 



P„ 



Br 



2 molecules of 

 sal-ammoniac. 



Molecule of the diatomic 

 bromide. 



It is not quite easy to frame a name for this complex body, in 

 which, under the influence of the diatomic ethylene, 2 molecules of 

 triethylphosphine are, if I may say so, dovetailed together. We have 

 in this case to deal with a compound molecularly representing 2 equi- 

 valents of chloride of ammonium, with phosphorus in the place of 

 nitrogen, bromine in the place of chlorine, 6 equivalents of ethyle and 

 1 equivalent of diatomic ethylene being substituted for the 8 equiva- 

 lents of hydrogen ; in fact, the compound is a dibromide of hexethyl- 

 ethylene-diphosphonium, sit venia verbo. 



Those who have accorded some attention to the direction of these 

 researches, cannot have failed to observe that the conception of the 

 compound which forms the subject of this note was the point from 

 which I started in examining the deportment of triethylphosphine 

 with dibromide of ethylene. In a note on polyammonias, presented 

 to the Royal Society about a year ago*, I first pointed out the exist- 

 ence of similar compounds in the nitrogen-series, adducing in favour 

 of this view such experimental evidence as I was enabled to collect 

 from the materials at hand. I have since endeavoured to expand 

 this evidence by the realization of a variety of bodies of analogous 

 constitution. For this purpose I have examined the action of am- 

 monia on dibromide of ethylene ; a process, which, owing to the num- 

 ber of bodies simultaneously produced, presents considerable difficul- 

 ties. With the view of simplifymg the reaction, I have passed step by 

 step to the primary, secondary, and tertiary monamines, in which the 

 advancing state of substitution promised a reduction of the number 

 of compounds capable of being generated under the influence of 

 dibromide of ethylene. These experiments, some of which have 

 been laid already before the Royal Society, whilst others are still in- 

 complete, have furnished many additional illustrations of the group 

 of polyammonias ; but most of these reactions are complicated, and 

 the compounds produced are far from always presenting the saUent 

 characters which I could have desired. In fact, it was not until 

 I pursued the inquiry into the phosphorus-series, and relying on 

 the promptness and precision with which these substances act, 

 examined the deportment of dibromide of ethylene with triethyl- 

 phosphine, that the experiments were attended with the desired 

 success. 



* Phil. Mag. vol. xvi. p. 309. 



