■588 
EESEAECHES OF DE. HOFjVIAXN- A2sB M. CAHOTES 
Chloride, Bromide, and Iodide of TnethylphospMne. 
Binoxide of triethylphosphine, when treated with hydrochloric, hydrobromic and 
hydriodic acids, is converted into the corresponding chloride, bromide, and iodide, which 
closely resemble the oxide in their general properties. They are hquids which gradually 
solidify in the exsiccator ; the crystals fuse at 100° and begin to volatilize, although their 
boiling-point is very high. The compounds of triethylphosphine with chlorine, bromine, 
and iodine may also be obtained by the action of these elements in aqueous or alcohohc 
solutions upon the phosphorus-base itself. Both methods, however, furnish products 
which are with difficulty purified. 
These compounds, as well as the saline compounds which the oxide of triethyl- 
phosphine produces with sulphuric and nitric acids, and which in the exsiccator gra- 
dually solidify into semi-crystalline masses, have but slightly occupied our attention, be- 
cause the formation of beautiful sulphur- and selenium-compounds enabled us to gain a 
sufficiently precise idea regarding the chemical characters of these substances in general. 
Bisulphide of Triethylphosphine. 
The remarkable phenomena which attend the combination of triethylphosphine 'v\-ith 
sulphur have been already described. The compound is likewise obtaiued by distilling 
triethylphosphine with cinnabar, which in this reaction is reduced to subsulphide or to 
metallic mercury. Treatment of the oxide with sulphuretted hydrogen or T^fith sulphide 
of ammonium does not furnish the compound. 
The best mode of preparing this beautiful body is the following. Flowers of sulphur 
are gradually introduced into a dilute solution of the phosphorus-base in ether. The 
liquid effervesces upon each addition, and the sulphur disappears. As soon as sulphur 
remaining undissolved indicates the completion of the reaction, the ether is volatilized, 
and the residuary mixture of free sulphur and bisulphide of triethylphosphine separated 
by boiling water. On cooling, the liquid deposits the compound in crystals of perfect 
purity. This sulphur-compound is one of the finest products with which we have 
become acquainted in the course of our inquiries. Its crystalhzing power is such, that 
by slowly cooling the solution most beautiful crystals may be obtauied, even in a test- 
tube, the liquid column being traversed by an aggregate of thin vertical needles, often 
five or six inches in length. The difference of the solubility of the compomid in cold 
and boiling water is very great ; indeed, but a minute quantity remains in solution 
at the common temperature. On adding an alkali to the cold solution the mixture 
becomes turbid, and deposits, after a few moments, small crystals. The sulphur-com- 
pound in this respect resembles the corresponding oxide, which is hkewise less soluble 
in alkalies than in pure water. This phenomenon is most strikmgly observed by adding 
potassa to a boiling saturated aqueous solution of the bisulphide ; it instantaneously 
separates in clear oily drops, which rapidly solidify into spherical aggregates of crystals 
as the liquid cools. The compound is even more readily soluble in alcohol and ether. 
