651 



with water in sonorous undulations, was found to be much greater 

 than that upon the ear connected with the same water by means of 

 a solid rod. When both tube and solid rod were employed simul- 

 taneously, sound was heard in that ear only supplied with the tube 



February 24, 1859. 

 Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 



The following communications were read : 



I. "Researches on the Phosphorus-Bases." No. V. Diphos- 

 phonium - Compounds. By A. W. HOFMANN, LL.D., 

 F.R.S., &c. Received January 20, 1859. 



In a note* on the deportment of dibromide of ethylene with tri- 

 ethylphosphine, I have stated that the reaction between these two 

 substances gives rise to the production of 



Bromide of triethylbromethylene- 1 r /Q g WQ H Br} PI Br 

 phosphonium ] ^ 4 5 ' 3 ^ 4 4 ' 



whilst two other bromides, viz. 

 Bromide of triethylphosphonium [(C 4 H 5 ) 3 HP]Br and 



[(C 4 H 5 ) 3 (C 4 H 3 )P]Br, 



are generated in consequence of secondary processes. But I did not 

 fail to remark in the same note, that in addition there is formed in 

 this reaction a fourth bromide, the nature of which, at that time, I 

 had been unable to fix by experiment. 



I have continued the study of this substance, which has led to the 

 following results. 



All attempts to eliminate the bromide in question by frequently 

 recrystallizing the direct product of the action of dibromide of ethyl- 

 ene on triethylphosphine have entirely failed. Considerable sacri- 

 fice of precious material and often repeated analyses of the different 

 crops of crystallization taught me nothing, except that the body 



* Proceedings, vol. ix. p. 287. 



