520 
DE. A. ^Y. HOFMAXN' OX THE PHOSPHOEES-BASES. 
According to Naumaxx : — 
a:b:c= 0-8533 : 1-1G89 : 1 ; a = 81° 53'; (3 = 88° 20'; y = 90° 36'. 
Forms observed : — 
oo P CO ; CO P CO ; OP; P' cc ; 2 P, oo ; P'. 
According to Weiss: — 
a:b:c = l: 1-1689 : 0-8533 ; ao5 = 98° 7'; = 90° 36'; coa= 91° 40'. 
Forms observed: — 
a:oob:ooc; coa:b:ooc; ooaioobic; oo cubic; — aibic; ooaibi — 2 c. 
According to Levy : — 
MT = 98°8'; TP = 91° 46'; PM = 90° 51'. 
• H:F:D = 0-8533:1-1689:1. 
Forms observed: — 
M, T, P, d\ e\ cl 
Combinations : — 
10 0, 010, 001 (Fig. 75). 
10 0, 01 0, 001;Tll (Fig. 76). 
100, 01 0, 001; 111, 02T 
10 0, 010, 001;Tll, 021, 011 (Fig. 77). 
Eig. 75. Eig. 76. Eig. 77, Fig. 7S. 
Cleavages 10 0 and 0 01: distinct and easily obtained. The cleavage is occasionally 
observed to take place during measuring, probably in consequence of the heat emanating 
from the face, "which has to be brought close on account of the minuteness of the crystals. 
Hemitropic crystals with the axis of hemitropy [0 0 1] (Fig. 78). It was possible to 
verify by measurement that the axis of hemitropy is really [0 0 1], and not a line per- 
pendicular to one of the faces of the crystal.” 
The phospharsonium-compounds, and more especially the hydrate of the series, are far- 
less stable than the corresponding- terms of the diphosphonium-series. 
If the product of the action of triethylarsine on the bromethylated monophosphonium 
be boiled with oxide of silver, instead of being treated in the cold, not a trace of the 
phospharsonium-compound is obtained. The caustic solution which is formed, fields, 
when saturated with hydrochloric acid and precipitated with dichloride of platinum, 
only the rather soluble octohedral crystals of the oxethylated tricthylphosphonium. 
