DE. A. W. HOEMAJra' ON THE PHOSPHOEUS-BASES. 
431 
observed occasionally small, well-defined yellow crystals disseminated among the mixture 
of white and red needles, which are deposited when the digestion-tubes are allowed to 
cool, before the transformation is terminated. The yellow crystals appeared in greater 
quantity towards the close of the operation, and were found to be a secondary product 
formed by the action of the sulphuretted hydrogen, which is generated in the last stage 
of the process. I have since learnt to prepare the yellow crystals by a simpler and 
more definite method. This remarkable compound has become the starting-point of a 
new inquiry, the result of which I reserve for a later communication. 
The formation of the red crystals by the union of triethylphosphine and disulphide of 
carbon takes place so rapidly, and with such facility, that ever since for the first time I 
observed this phenomenon, I have used the disulphide of carbon as a reagent for the 
detection of the phosphorus-bases ; for trimethylphosphine exhibits a deportment per- 
fectly similar to that of the ethyl-body. The minutest quantities of these bases may 
thus be readily and safely recognized. The reaction is best observed by pouring the 
liquid to be examined upon a watch-glass, and allowing the vapour of the disulphide of 
carbon to flow from an inclined bottle upon the liquid. Immediately the watch-glass is 
coated with a beautiful net-work of the red crystals. It requires scarcely to be men- 
tioned that the crystals are not formed when the phosphorus-bases are combined with 
acids. They appear, however, readily on adding to a mixture of their salts and 
disulphide of carbon, a drop of potash, which liberates the bases. 
On the other hand, triethylphosphine may be employed with the greatest advantage 
as a test for disulphide of carbon. There is, in fact, no test for this substance, which 
in delicacy could be compared with it. By its aid the presence of the disulphide in the 
most volatile fractions of coal-tar-benzol is readily proved ; even the exceedingly small 
quantity of disulphide of carbon diffused in the most carefully purified coal-gas may, as 
I have shown already in another place*, be recognized without any difficulty. When 
the gas is passed thi'ough a bulb-apparatus containing ether to which a few drops of 
triethylphosphine are added, the liquid soon assumes a reddish tint, which gradually 
increases in intensity, until, when the. ether is evaporated, the interior of the apparatus 
appears coated with a delicate efflorescence of the red crystals. Scarcely more than 
half a cubic foot of the present London coal-gas is required for this experiment. 
In order to satisfy myself that disulphide of carbon may be employed with safety as a 
test for the phosphorus-bases, it was necessary to examine the deportment of this com- 
pound with the arsines and stihines. Disulphide of carbon exhibits no reaction with tri~ 
etliylarsine and triethjlstihine. I have left mixtures of these bases with the disulphide 
in contact for a considerable length of time, both at the common temperature and at 
100°, rvithout being able to observe the slightest alteration. I have also satisfied myself 
that disulphide of carbon, at all events at the common temperature, is without action 
upon jphosphoretted hydrogen. 
* Quarterly Journal of the Chemical Society, vol. xiii. p. 87. 
