Dr. Hofmann on the Phosphorm-Bases. 135 



of triethylphosphine and 1 equiv. of bibromide of ethylene, 

 C, H,, P + C, H, Br, = C,, H,3 PBr,. 



The bromine in this compound exists in two perfectly different 

 forms ; addition of nitrate of silver precipitated only one-half of this 

 element as bromide of silver, while even by protracted ebullition the 

 second half remained untouched. The result changed, however, on 

 digestion with freshly precipitated oxide of silver, when the whole of 

 the bromine separated at once in the form of bromide of silver. 



On adding to the solution of the bromide an excess of nitrate of 

 silver, filtering off the bromide, and removing the excess of silver by 

 hydrochloric acid, a corresponding chloride was obtained, from which 

 bichloride of platinum precipitated a beautiful orange-yellow pla- 

 tinum-salt. In a moderately diluted solution which had been pre- 

 viously gently heated, no immediate precipitate was produced ; but 

 on coohng, the same salt was deposited in magnificent needles, which 

 could be recrystallized from boiling water, or better from hydro- 

 chloric acid. This compound contained 



C,, H,g BrPCl, PtCl,. 



A difiicultly soluble gold-salt, crystallizing from boiling water in 

 small scales, was found to have the corresponding composition, 

 C,« H,, BrPCl, AUCI3. 



Very different results were observed when the whole of the bromine 

 was removed by means of oxide of silver. A powerfully alkaline 

 solution was thus obtained, which, converted into hydrochlorate, gave, 

 with bichloride of platinum, a precipitate only after very considerable 

 evaporation. The precipitate was likewise of a deep orange-red 

 colour ; it readily dissolved in boiling water, from which it separated 

 on cooling in the form of well-defined octahedra having the compo- 

 sition 



C,eH,3PCl,PtCl,. 



Terchloride of gold furnished Ukewise a crystalline precipitate 

 very similar in appearance to the gold-salt previously mentioned, but 

 containing 



C,3H,,PCl,AuCl3. 



The action of bibromide of ethylene on triethylphosphine, and 

 the subsequent transformation of the compound produced, is readily 

 explained. The two substances unite in equal equivalents, the product 

 of the reaction being the bromide of a phosphonium, in which the 

 fourth equivalent of hydrogen is replaced by a compound molecule, 

 C^HjBr (brominetted ethyle?), of monatomic substitution-power. 



Bromide of triethyl-bromethylene-C, H^ I „ 



phosphonium CjHj ( 



(C.H.Br)' J 



The compound phosphonium of this bromide possesses very con- 

 siderable stability, as is sufficiently evinced by its deportment with 

 iiitratc of silver, and by the formation of the platinum- and of the 



