214 ‘PROFESSOR LETTS AND N. COLLIE ON THE 
The higher boiling residue passed between 280°-300°, and solidified in the 
condenser. It was dissolved in alcohol, and recrystallised several times. The 
recrystallised substance had the characteristic form and melting point (118° C.) 
of stilbene. 
In the mother liquors there remained a solid of lower melting point, and 
having the odour of dibenzyl; but its quantity was too small to enable us to 
identify it absolutely. We think that there can be but little doubt that 
it consisted of that body. 
No chloride of benzyl could be found, although the liquid product certainly 
smelt of it. Its quantity was therefore insignificant. 2 
This experiment shows that the phosphonium chloride is not dissociated by 
heat, but splits up in a somewhat complicated manner. Very possibly the first 
action of heat is to give stilbene, hydrochloric acid, and tribenzyl-phosphine. 
C H,) — X = = = = a 
F Oe Mote P01) = 2C;Hy)gP + OyH,—CH=CH-O,H, + 2HCl. 
5 
The phosphine splitting up later into toluol, stilbene, and dibenzy]. 
C,H,—CH:H C,H,—Ca—Ch CG He 4 C,H Ore 
2(C,H;-OHH —SP} = ‘ 
C,H,—CHH: +C,H;—CH,—CH,—C,H; + 2P. 
It is however quite possible, considering the large quantity of toluol which 
is formed in proportion to the stilbene, and also considering the considerable 
amount of charred matter which remains, that the tribenzyl-phosphine splits up 
into toluol, and the residue C,H;—C,] only, the latter becoming carbonised. 
cath = c= + 2C,H,—CH,. 
Action of Heat on the Acid Sulphate.—8 grms. of the acid sulphate were 
carefully dried, and heated in a small retort connected with a wide con- 
densing tube. The salt fused, then effervesced violently, and a colourless liquid 
distilled which solidified in the condenser. Sulphurous anhydride was given 
off at the end of the operation, and a slight residue of syrupy consistency 
and of a dark brown colour remained in the retort. The crystalline product 
was washed with alcohol until quite colourless, and then recrystallised several 
times from the same liquid, in which it was not very soluble. It crystallised 
in very thin needles of considerable length. These melted at 205°-206° C. 
It did not precipitate chloride of barium, but contained sulphur, as it gave 
the sulphuric acid reaction after it had been oxidised with a mixture of 
