564 PROF. LETTS AND MR R. F. BLAKE ON 



ethereal solution was filtered off, and distilled to dryness in a current of hydrogen. 

 The residue thus obtained weighed from 20-30 grms. 



It was submitted to distillation under diminished pressure, the distilling flask con- 

 taining it being immersed in a bath of fusible metal. Average pressure during 

 distillation 90 mm. ; temperature of fusible metal, 260°-300° C. ; temperature of liquid 

 distilling over, 100°-180°. The distillation was stopped after about one-fifth of the 

 total product had passed over, as signs of decomposition began to appear in the residue. 



The distillate was a colourless liquid. The residue when cold, a fluorescent, viscous 

 (almost solid) mass. The distillate had the following properties : — 



(1) Exposed to the air it oxidised violently, and gave white fumes ; it grew so hot 

 that a vessel containing it could not be touched. A syrup resulted. This had an acid 

 reaction, and dissolved for the greater part in potash solution, leaving a slight residue, 

 which was viscous. On adding hydrochloric acid to the potash solution, no precipitate of 

 dibenzyl phosphinic acid was produced. On adding sulphate of copper to the neutralised 

 potash solutions, no precipitate was produced in the cold, but on warming, the charac- 

 teristic precipitate of monobenzyl phosphinite of copper was thrown down. 



(2) Treated with crystallised benzyl iodide, the mixture grew slightly warm, and from 

 the product only a very small quantity of iodide of tetrabenzyl phosphonium could be 

 obtained. 



These results show that monobenzyl phosphine was contained in the distillate, and 

 probably only minute quantities of di- or tribenzyl phosphine. 



Our experiments so far, have undoubtedly shown that the semisolid mass which is left 

 on digesting the sealed tube product with potash, &c, contains both the secondary and 

 tertiary phosphines, but whence comes the primary phosphine ? Provisionally, we must 

 assume that it is derived from the destructive distillation of the secondary phosphine. 



2(C 7 H 7 ) 2 P = (C 7 H 7 )PH 2 +(C 7 H 7 ) 3 P , 



and that the tertiary phosphine also is scarcely volatile without decomposition. 



It was at all events proved that we need not attempt to isolate the secondary and 

 tertiary phosphine by distillation, and that some other method must be devised. 



Experiment 5. — The contents of twelve sealed tubes were treated as before with steam, 

 and afterwards with potash, &c. The remaining semisolid cake of phosphines weighed 

 about 97 grms. 



The cake was treated with a considerable quantity of ether, and the residue (A) 

 reserved for examination. The filtered ethereal solution, together with the ethereal 

 washings from the insoluble matter, were left undisturbed for about sixteen hours, when a 

 good deal of crystalline matter (B) was precipitated. On filtering from this, and 

 adding an additional quantity of ether to the solution, more insoluble crystalline matter 

 was precipitated. The addition of ether was continued until no further precipitation 

 occurred. 



The filtered ethereal solution was then boiled to dryness in a current of carbonic 



