238 Dr. A. W. Hofmarm on the Phosphorus Bases. [Mar. 21, 



easily be obtained in a state of purity for analysis. In this experiment, 

 occasionally, well-formed tables are produced of considerable dimensions 

 and great beauty. The salt has the composition — 

 C 7 H 10 PI = (C 7 H 7 ) H 2 P. HI. 



Benzylphosphine combines likewise with concentrated chlorhydric and 

 bromhydric acids. I have not, however, been able to obtain these com- 

 pounds in crystals. The chlorhydrate gives with platinum perchloride a 

 yellow insoluble precipitate. 



Benzylphosphine is formed according to the equation — 

 2C 7 H 7 C1 + 2[H 3 P.HIJ + Zn 0=2[(C 7 H 7 ) H 2 P.HI] + Zn Cl 2 +H a O. 



This equation, however, shows only one phase of the reaction, in which 

 at the same time several other substances are formed. 



Dibenzylphosphine. 



C 7 H 7 ] 

 C u H l5 P=C 7 H 7 lp. 



This compound is found in the liquid remaining in the retort after the 

 distillation of benzylphosphine. By long standing, especially in the presence 

 of solid alkali, this fluid solidifies to a soft mass of crystals, which are 

 collected on a linen filter, in order to free them, by pressing, as much as 

 possible from adhering liquid. The still strongly coloured crystals are 

 then dissolved in alcohol and treated with a little animal charcoal. The 

 colourless liquid thus obtained deposits on cooling beautiful white crystals 

 of the new compound. By repeated crystallization from boiling alcohol, 

 dibenzylphosphine is obtained in a perfectly pure state. Thus prepared, 

 the phosphine forms large brilliant needles, mostly grouped in stars or glis* 

 tening tufts, perfectly tasteless and colourless, which are insoluble in water, 

 but dissolve, though sparingly, in boiling alcohol. In ether they are 

 nearly insoluble. The crystals melt at 205° ; at a higher temperature 

 they are volatilized, but not without partial decomposition. With the 

 entrance of the second benzyl group, the basic characters, which in the 

 monobenzylphosphine are still distinctly perceptible, have entirely disap« 

 peared. Dibenzylphosphine does not dissolve in acid, nor have I succeeded 

 in obtaining a platinum salt. In this respect the aromatic secondary phos- 

 phine essentially differs from the analogous bodies in the ethyl and meil. J I 

 series, which are well-marked bases. The absence of basic properties 

 cannot, however, be looked upon as strange, since even in the secondary aro- 

 matic amines we find the tendency to form saline compounds very nearly 

 effaced. The difference of dibenzylphosphine from the corresponding 

 terms in the methyl and ethyl series becomes obvious, moreover, by its 

 behaviour with oxygen ; for whilst dimethyl- and diethylphosphine take 

 fire on contact with air at the ordinary temperature, oxygen is without 

 any action, even at an elevated temperature, on the dibenzylated phosphorus 



