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



(2) Combustion with pure oxide of copper. 



c 10432 C0 2 =0-284509 C = 7528 per cent. 

 03779 gave I 02258 H 2 =0025088 H=663 

 ( 01277 Mg 2 P 2 7 = 00356639 P= 943 



Obtained. 



Calculated for (CfH^PO., 





I. 



II. 





Carbon, 



75-28 



7575 



7500 



Hydrogen, 



6 63 



660 



6-25 



Phosphorus, . 



9-43 



... 



922 



It is very singular that this substance has the same melting point as sulphide of 

 tribenzyl phosphine, and precisely the same solubility relations. The percentage amounts 

 of carbon, hydrogen, and phosphorus are also identical. Its crystalline habit is, however, 

 different, and we were unable to detect any sulphur in it, whereas by the test we 

 employed (ignition with caustic potash and chlorate of potash) we readily found the 

 sulphur in a specimen of the sulphide. 



We had not sufficient of the substance to study its properties exhaustively, but we 

 ascertained that it readily yielded oxide of tribenzyl phosphine. This we accomplished 

 by dissolving it in hot acetic acid, and adding bromine, in excess, when the characteristic 

 compound of the oxide separated, which was identified by analysis. 



Analysis. 



0-6789 required 223 c.c^ AgN0 3 = 0-1784 Br = 2627 per cent. 



Mean of ten Determinations of 

 Obtained. the Bromine Compound of 



Tribenzyl Phosphine Oxide. 

 Bromine, .... 26"27 26-70 



A quantity of the brominated body was boiled with caustic soda solution, and the 

 product, after washing, recrystallised. Its melting point was now found to be 215°-215°'5 

 — exactly that of the oxide, and it had its crystalline form. 



It is very improbable that a tertiary phosphine peroxide could be formed under the 

 conditions in which the substance in question was produced, and as yet no such body 

 has been described. But it seems equally improbable, from the properties of the sub- 

 stance, that it is the isomer, viz., dibenzyl phosphinate of benzyl, 



C 7 H 7 ^~^-^^ 



C 7 H 7 /P = 0. 



C 7 H 7 -0/ 



We therefore remain in doubt as to its nature. 



We have thus separated from the products of Hofmann's sealed tube reaction the 

 following ten bodies (or have proved them to be present) : — 



