DE. A. W. HOFMAm ON THE PHOSPHOEIJS-BASES. 
485 
Analysis has furnished the following numbers : — 
I. 0*4465 grm. of double salt, fused with carbonate of sodium, left, after removal 
of the bromide of sodium, a silver-residue, which, when treated with nitric and hydro- 
chloric acid, gave 0*1042 grm. of chloride of silver. 
II. 0*6442 grm. of double salt gave, on boiling with water, a residue of 0*2710 grm. 
of bromide of silver; the filtrate yielded with nitiate of silver an additional amount 
of 0*3220 grm. of bromide of silver; the total amount of bromide of silver obtained 
being therefore 0*5930 grm. 
III. 0*7065 grm. 
of bromide of silver. 
of double salt gave by treatment with nitrate of silver 0*6538 grm. 
Theory. Experiment. 
A 
r 
r 
I. II. 
A 
III. 
Cl 4 
168 
27*45 
H34 
34 
5*56 
P2 
62 
10*13 
108 
17*65 
17*5'6 
Br3 
240 
39*21 
39*17 
39*37 
612 100*00 
The salt crystallizes, but not 
readily, from 
boiling alcohol. It is 
immediately decom^ 
posed by water, bromide of silver being separated, and the bromide of the diphosphonium 
passing into the solution. 
In describing the general character of the action of dibromide of ethylene upon tri- 
ethylphosphine, I have mentioned that, in addition to the monatomic and diatomic 
bromides, which are the principal products of the reaction, secondary compounds may be 
formed, but always in comparatively small quantities. The mother-liquors generally 
contain oxide of triethylphosphine, formed by the action of the atmosphere ; they contain, 
moreover, bromide of triethylphosphonium, if the dibromide had not been carefully 
deprived of hydrobromic acid. The bromide of triethylphosphonium, however, under 
certain conditions, arises from the scission of dibromide of ethylene into hydrobromic 
acid and bromide of vinyl, the latter producing in this case the bromide of vinyl- 
triethylphosphonium. I had an opportunity of establishing this fact experimentally, 
when preparing a considerable quantity of the dibromide of the diphosphonium. The 
phosphorus-base having been employed in excess in this operation, not a trace of the 
bromethylated monophosphonium had been formed, the absence of which was carefully 
proved by a special experiment. The bromides were then transformed into chlorides 
and the latter precipitated by dichloride of platinum ; the mother-liquor filtered off from 
the copious precipitate of the diphosphonium-salt was considerably evaporated, when, on 
cooling, well-formed octohedra were deposited, which were recrystallized from water. 
0*4835 grm. of platinum-salt, treated with sulphuretted hydrogen, &c., gave 0*1365 
grm. = 2 8*2 3 per cent, of platinum. 
