414 
DE. A. W. HOEMAXX OX THE PHOSPHOEUS-BASES. 
of triethylphosphine is 44° ; the point of solidification at the same temperature. It boils 
at 240° C. (corrected). 
As no determination of the vapour-density of any member of the group of compounds 
to which the oxide of triethylphosphine belongs has yet been made, it appeared to me 
of some interest to perform this experiment with the oxide in question. Since the deter- 
mination by Dumas’ method could not have been performed without sacrificiog a con- 
siderable amount of material, and Gat-Lussac’s was inapplicable on account of the high 
boiling-point of the compound, I adopted a modification of the latter, consisting essen- 
tially in generating the vapour in the closed arm of a U-shaped tube filled with mercury 
and immersed in a copper vessel containing heated paraffin, and calculating its volume 
from the weight of the mercury driven out of the other arm. As I intend to publish a 
full description of this method, which promises to be very useful in certain cases. I 
shall here content myself with stating the results obtained in one of the experiments. 
Substance O’loO grm. 
Volume of vapour 49'1 cub. cent. 
Thermometer (corrected) 266°'6 C. 
Barometer at 0° C . 0-7670 metre. 
Additional mercury column at 0°C. . . 0-1056 meti-e. 
These numbers prove the vapour-density of oxide of triethylphosphine to be 66-30, 
referred to hydrogen as unity, or 4-60 referred to atmospheric air. Assuming that the 
molecule of oxide of triethylphosphine corresponds to 2 vols. of vapour*, the cal- 
134 
culated specific gravity of its vapour =—=67, when referred to hydi-ogen, and 4-63 
when referred to air. Hence we may conclude that in oxide of triethylphospliine, the 
elements are condensed in the same manner as in the majority of thoroughly investigated 
organic compounds. 
From the facility with which triethylphosphine is converted into the oxide by expo- 
sure to the air, even at ordinary temperatures, and from the A ery high boiling-point of 
the resulting compound, in consequence of which its vapour can exert but a very slight 
tension at ordinary temperatures, I am induced to think that the phosphorus-base may 
be used in many cases for the volumetric estimation of oxygen. Vlien a paper ball 
soaked in triethylphosphine is passed up into a portion of air confined over mercury, the 
mercury immediately begins to rise, and continues to do so for about two hom-s, after 
which the volume becomes constant, the diminution corresponding A ery iieai'ly to the 
proportion of oxygen in the air. To obtain Aery exact results, hoAvever, it would pro- 
bably be necessary in every case to remove the residual Aapour of triethylphosphine by 
means of a ball saturated Avith sulphuric acid. 
Oxide of triethylphosphine exhibits in general but small tendency to unite with other 
bodies ; nevertheless it forms crystalline compounds with iodide and bromide of zinc. I 
have examined more particularly the zinc-iodide-compound already mentioned. 
* Ho 0 =2 Tols. of vapour. 
