DE. A. W. HOFMANN ON THE PHOSPHOEUS-BASES. 
479 
The di-iodide forms, with various metallic salts, crystalline double compounds, among 
which I have more particularly examined the zinc-salt; its analysis will be given further on. 
Lifluoride. — The solution of the hydrate, neutralized with hydrofluoric acid and dried 
over sulphuric acid, leaves a colourless transparent syrup, which does not crystallize, even 
after standing for a considerable length of time in air or in vacuo. The fluorine-com- 
pound, like the other diphosphonium-salts, is soluble in alcohol but insoluble in ether. 
Silico-fluoride. — The solution, neutralized with hydrofluosilicic acid, likewise failed to 
yield crystals by evaporation. 
IHcyanide. — The solution of the hydrate, mixed with excess of hydrocyanic acid, retains 
its alkaline reaction ; when evaporated on the water-bath, it gives off every trace of hydro- 
cyanic acid. On digesting a solution of the di-iodide with excess of cyanide of silver, a 
double compound dissolves, which crystallizes in splendid needles, but is likewise decom- 
posed by evaporation, with evolution of hydrocyanic acid and separation of cyanide of 
silver. 
iJisulphocyanate. — When a solution of the di-iodide is boiled with excess of recently 
precipitated sulphocyanate of silver, a solution of the disulphocyanate is obtained, per- 
fectly free from silver, and solidifying by evaporation on the water-bath into a crystalline 
mass. The salt dissolves readily in water and in alcohol, and is precipitated therefrom 
by ether. The aqueous solution is likewise precipitated by potassa, the oily drops thus 
separated gradually solidifying into crystalline rosettes. 
Iknitrate. — This salt, prepared by saturating the base with nitric acid, forms laminar 
crystals, permanent in the air, extremely soluble in water, less soluble in alcohol, and 
precipitated from the alcoholic solution by ether, as an oil which gradually solidifies. 
The solution forms with mercuric chloride a precipitate which crystallizes in needles. 
iJipercldorate. — This salt is perhaps the most beautiful of the diphosphonium-com- 
pounds. On mixing moderately concentrated solutions of the hydrate and perchloric 
acid, the liquid is soon traversed by delicate crystalline needles, often an inch long. 
They may be recr^^stallized from boiling water and dried at 100'^ without decomposition. 
At a higher temperature, they are decomposed, with slight detonation. 
In the analysis of the perchlorate, the diphosphonium was weighed in the form of the 
nearly insoluble platinum-salt. 
0'3130grm. of diperchlorate, evaporated to dryness with an excess of dichloride of 
platinum, gave, after treatment with alcohol, 0‘4535 grm. of the diphosphonium-platinuin- 
salt. 
^14 ^2 ^^2 ^8 — 
1 equiv. of Diphosphonium 
2 equivs. of Chlorine 
8 equivs. of Oxygen . 
1 equiv. of Diperchlorate 
(c,h,)3pJ" 
Theory. 
. . 264 
67-02 
. . 71 
15-33 
. . 128 
27-65 
. . 463 
100-00 
Experiment. 
56-71 
