496 
DE. A. ^Y. HOEArAXX OX THE PHOSPHOEES-BASES. 
The crystals of the forai Fig. 50 are most frequent ; they seem to have adhered to 
the vessel with one of the larger faces of the prism 101. 
Crystals distinct. Lustre on the faces, except 111, very great. 
Crystals optically positive. The indices of refraction are for the ordinar}' ray co = 1-660. 
for the extraordinary ray € = 1-668. 
The crystals of iodide of tetrethylphosphonium are isomorphous "svith those of iodide 
of silver. In the latter substance. 111, 10 0 = 58° 27', instead of 59° 32', found in the 
tetrethylphosphonium-salt. Both salts have the same hexagonal habitus, and both are 
optically positive.” 
Crystalline Form of the Platinum-salt of Tetrethylphosphonium. 
“ System monometric : — 
Forms observed : — 
10 0, 111 (Fig. 53). 
Angles. Calculated. Obser\-ed. 
0 01,1 11 = 54° 44 54° 40 
111, 111 = 70 32 70 36 
Fig. 53. 
The faces of the cube 10 0 are very brilliant ; those of the octohedi-on 111 are often 
hollow. 
No influence on polarized light. 
Colour orange-red.” 
