332 PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 
Crarts and Sitva also passed hydrobromic acid gas into the dry phosphine 
oxide, and distilled the product. It began to boil at 260°, and about half passed 
over at 270-°300° C. A residue was left in the retort at 310°, which began to 
decompose. 
The author considered it advisable to repeat this experiment. 
Action of Hydrobromic Acid on Oxide of Triethyl-Phosphine. 
7-8 germs. of the oxide were fused and a current of hydrobromic acid passed 
through it. The gas was absorbed eagerly, much heat was disengaged, and the 
product was coloured brown. As soon as the hydrobromic acid ceased to be 
absorbed, the product was submitted to distillation. Below 300° a little liquid 
passed over, the thermometer then rose slowly, whilst a colourless liquid passed 
over, which solidified on cooling. It had much the same appearance as the 
volatile product obtained by heating bromacetic acid and triethyl-phosphine, 
but it did not solidify quite so readily as that substance. The thermometer 
was tolerably constant from 320°-325° C., but a good deal of residue remained 
above this temperature. In another experiment the oxide of the phosphine 
was not saturated with hydrobromic acid, but was treated with rather more 
than 30 per cent. of its weight of the gas, which as before was eagerly absorbed. 
On distilling the product thus obtained only a few drops of liquid passed below 
303°. But from this temperature to 308° almost every drop of the product 
passed over, and solidified on cooling to a white solid. 
A determination of the bromine which it contained was made with the 
following results :— 
03968 required 15:8 cc. decinormal AgNO,=31'9 per cent. Br 
0:4761 sup jloOas 7 5 Peels 
2 
Although these numbers are somewhat higher than those obtained with the 
product of the action of heat on bromacetic acid and triethyl-phosphine, the 
difference is but slight, and very probably it would have been even less had the 
substance been re-distilled. 
The author considers that there can be no doubt as to the nature of the 
volatile body obtained by heating the triethyl-phosphine and bromacetic acid ; it 
is simply a compound of phosphine oxide with hydrobromic acid, or a mixture 
of the two substances, similar to hydrobromic acid, or hydrochloric acid solu- 
tions of constant boiling point. 
Crarts and Sitva take the latter view of the nature of the substance 
obtained by them by the action of hydrobromic acid on the phosphine oxide. 
In the memoir already quoted they say, ‘“‘ Hydrobromic, like hydrochloric acid, 
combines with the oxide of triethyl-phosphine in the same way that these acids 
combine with water, and it is only under exceptional circumstances that a com- 
ae ie ae iy 
