DE. A. W. HOFMANN ON THE PHOSPHOEHS-BASES. 
461 
The formula 
Cg Hi, Br P Au Cl, = [{C, Br) (C^ P] Cl, Au Cl, 
requires the following values : — 
Theory. 
< ^ ' 
1 equiv. of Phosphonium . . . 226 40-00 
4 equivs. of Chlorine .... 142 25-13 
1 equiv. of Gold 197 34-87 
1 equiv. of Gold-salt .... 565 100-00 
Experiment. 
35-12 
I have in vain endeavoured to prepare the hydrate 
belonging to these salts. 
In quoting the analysis of the bromide, I have already mentioned that this salt, when 
treated with oxide of silver, gives up the whole of its bromine. On mixing the caustic 
liquid filtered from the silver-salt with hydrochloric acid and dichloride of platinum, we 
no longer obtain the sparingly soluble platinum-salt crystallizing in the characteristic 
needles ; but the liquid, after being considerably concentrated by evaporation, yields 
well-defined, reddish-yellow octohedra belonging to another base. An exactly similar 
result is obtained on attempting to separate the base from the sulphate by means 
of baryta. After filtering off the sulphate of barium, there remains a strongly alkaline 
liquid, which likewise yields only the octohedral platinum-salt, while the presence of 
bromide of barium in the solution indicates the transformation of the original molecular 
system. The elimination of the second equivalent of bromine by silver-salts, which 
takes place instantly and completely in alkaline liquids, may likewise be effected by 
continual ebullition in neutral and even in acid solutions, though always slowly and 
incompletely. If the bromide be precipitated by excess of nitrate of silver, the filtered 
liquid, on being boiled and evaporated, deposits a fresh quantity of bromide of silver ; 
but in most cases, even after long-continued boiling, a considerable quantity of bromine 
remains latent, and may be immediately recognized by again filtering- the liquid and 
slightly supersaturating it with ammonia, the whole of the remaining bromine being 
then precipitated as bromide of silver. This deportment furnishes in fact a character- 
istic distinction of the bromethylated bromide, by which this substance may often be 
conveniently recognized. It deserves to be remarked that the fixed caustic alkalies exert 
but a slight action on the bromethylated bromide ; the compound is precipitated by 
the alkalies from its cold aqueous solution in the crystalline state and without decompo- 
sition, and it is only after some time that alterations take place, probably affecting its 
intimate constitution. The nature of these alterations has not yet been made out. The 
crystals may be boiled for some time with alcoholic solution of potassa without decom- 
position. The bromide likewise sufiers no alteration by continued digestion with water 
or alcohol at 100°. 
