DE. A. W. HOFMAJsW ON THE PHOSPHOETJS-BASES. 
423 
Angles. Calculated. 
O / 
101, 
Oil 
= 
60 
0 
lOT, 
211 
= 
30 
0 
lOT, 
210 
= 
50 
56 
10 1, 
120 
71 
38 
2TT, 
210 
= 
56 
55 
211, 
120 
= 
90 
0 
210, 
120 
36 
44 
210, 
021 
= 
66 
10 
210, 
012 
= 
78 
9 
Observed. 
Eig. 13. 
66 20 
According to Naumanji : — 
Forms observed : — 
According to Weiss : — 
Forms observed : — 
According to Levy : — 
Forms observed : — 
Combinations observed : — 
K=90° 13'. 
CO P 2, CO R, f P 2. 
«=0-8211. 
a\\a \ a\^c\ ooa: a: a'.ooc; a\\a\a\\G. 
PP=90° 13'. 
If. 
101, 210 (Fig. 14). 
10 1 , 210 ; 21 1 . 
The summit of the hexagonal prisms is almost always badly terminated, since they 
are frequently hollow : bright faces 210 are but rarely met with. In one single case 
2 1 1 could be distinctly traced. The general habitus of the crystals is that of thin, 
long, hexagonal needles. At summer heat, the crystals are very soft and flexible ; they 
may be bent 180° without breaking. At lower temperatures, they are harder and much 
less flexible. 
The crystals are optically positive. It is possible to measure the deviation through the 
faces of the hexagonal prism, whence it may be inferred that the index of refraction for 
the extraordinary ray €=1-65, and for the ordinary ray ct)=l’59.” 
Behaviour of Triethylphosphine ivith Sulphuretted Hydrogen. 
The phosphorus-base has no action on sulphuretted hydrogen. When it is brought in 
contact with hydrosulphuric acid over mercury, the gas does not exhibit any alteration. 
No sulphide of triethylphosphine is formed even in presence of air, as might indeed have 
been expected. The attraction of the phosphorus-base for oxygen prevents the oxida- 
