DE. A. HOFMAJ^N ON THE PHOSPHOEUS-BASES. 
411 
On extracting the brown residue in the tubes with warm water, and evaporating the 
clear solution, an oily substance separates which covers the bottom of the dish, and on 
cooling solidifies into a mass of hard crystals. By repeatedly crystallizing this substance 
from boiling water and from alcohol, large crystals are obtained, which give off triethyl- 
phosphine when treated with potassa even in the cold, and are found to consist of a com- 
pound of iodide of zinc with iodide of triethylphosphonium. 
I. 0'3721 grm. of the compound dried at 100°, when burnt with a mixture of chromate 
of lead and oxide of copper*, gave 0-2435 grm. of carbonic acid and 0-1320 grm. of water. 
II. 0-3274 grm. of substance gave 0-3789 grm. of iodide of silver, 
III. 0-3800 grm. of substance gave 0-4370 grm. of iodide of silver. 
These experiments lead to the formula 
C, H,s P Zn I 2 = [(C^ HJ 3 H P] I, Zn If. 
Theory. 
Experiment. 
A 
I. 
II. 
III. ' 
Ce 
72 
17-75 
17-85 
Hi6 
16 
3-95 
3-94 
• 
P 
31 
7-65 
Zn 
32-5 
8-01 
I2 
254 
62-64 
62-52 
62-13 
405-5 
100-00 
A solution of iodide of triethylphosphonium mixed with iodide of zinc immediately 
gives a crj^stalline compound of exactly similar characters. 
The mother-liquor of the double salt yields, when further evaporated, another crystal- 
line body which is more difficult to purify. After three or four crystallizations, how- 
ever, well-developed crystals are obtained, which do not yield triethylphosphine when 
treated with potash, either in the cold or with aid of heat. The analysis, to be given 
further on, shows that this crystalline substance is a compound of iodide of zinc and 
oxide of triethylphosphine, 
Cg P O, Zn I=(C 2 H -)3 P O, Zn I. 
The third compound, which remains in the mother-liquor after the two former have 
crystallized out, and separates, on further evaporation, in beautiful needle-shaped 
crystals, may be recognized without difficulty as iodide of tetrethylphosphonium. The 
crystals are insoluble in cold potassa-solution, and give otf triethylphosphine only when 
heated with solid hydrate of potassium. 
* The combustion of the phosphorus-compounds is not very easily effected. The experiment succeeds 
best with a mixture of chromate of lead and oxide of copper. All the carbon-determinations quoted in the 
following pages have been made with this mixture, unless another mode of proceeding is specially stated. 
AH the substances analysed were dried at 100°, except in a few cases, when the mode of drying is also 
specially mentioned. 
t H=l; 0=16, S=32; C=12. 
3 I 2 
