PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 333 
pound with a simple chemical formula is formed.” The author, however, is by 
no means convinced of the correctness of this statement, for the numbers 
obtained by them agree very well (as he has shown) with a simple chemical 
formula, and although the latter does not consist of one molcule of the oxide and 
one molecule of the acid, it must be remembered that phosphine oxides combine 
with other bodies frequently in somewhat indefinite molecular proportions, in 
the same manner that silicic acid combines with bases. Further experiments 
are, however, necessary to decide the question. 
The action of heat on the product of union of triethyl-phosphine and 
bromacetic acid cannot be expressed by any simple equation. 
It is, however, probable, from the fact that some bromide of acetyl is 
evolved, that the first action of heat is as follows :— 
Br 
(CoH) =PC = (C,H,),PO+CH,—COBr. 
~ CH, 
The phosphine oxide then removes hydrobromic acid from the bromide of 
acetyl, and the residue CH,—CO becomes carbonised. 
Action of Bromide of Acetyl on Oxide of Triethyl-Phosphine. 
Whilst the experiments which have just been described were in progress, 
and the author had come to the conclusion that, under certain conditions, 
bromacetic acid and triethyl-phosphine unite to form the aceto-bromide of 
triethyl-phosphine, Dr Crum Brown suggested that it would be worth while 
to try the action of bromide of acetyl on the oxide of triethyl-phosphine, as 
by that means the same body ought to be formed. 
(0,H,),=P=0+CH,—COBr = (0, HPC 
OOC -—CH,. 
The experiment was accordingly tried. 
The two substances react with energy, and if they are undiluted much 
heat is evolved, the mixture grows brown, and on cooling solidifies to a 
buttery mass, having exactly the same appearance, and, so far as could be ascer- 
tained, the same properties as the product of action of bromacetic acid on triethyl- 
phosphine. 
On heating, this product behaved exactly like the latter ; hydrobromic acid 
and a small quantity of bromide of acetyl passed over first ; the thermometer * 
then rose to 308° C., and remained stationary at that temperature, whilst a 
colourless liquid distilled, which solidified on cooling, and had the appearance 
* The thermometer employed was different from that used in previous experiments, and the author 
cannot vouch for its accuracy. 
VOL. XXX. PART L 3 E 
