428 
DE. A. W. HOKMAXy OX THE PHOSPHOEUS-BASES. 
Cleavages : — 
010 veiy distinct and easily obtained, although sometimes slightly curved. 
10 0 easily obtained and fibrous. 
The crystals are optically positive : the medium-hne coincides -with the axis of sym- 
metry [010], and the angle of the optical axes is considerable ; in a plate parallel to 
010, the beginning of the rings may be seen, theh centres being imisible. The centres 
may be seen, however, with the aid of a glass prism ; and from this obsen ation. together 
with the fact that the indices of refraction are not very far from Irio, it may be infeired 
that the interior angle of the optical axes is not very difierent from 7 0°. The plane of 
the optical axes is nearly parallel to the face 0 01; it deviates only by a few degrees, 
exhibiting a tendency to approach the plane perpendicular to 1 0 0. Tlie axis of s}Tnme- 
try, or of smallest elasticity, exhibits a violet-red coloiu, which even in very thin layers is 
very intense. The axis nearly parallel to [1 0 0], or the axis of greatest elasticit}', exhi- 
bits a similar but much lighter red tint ; the axis of mean elasticity shows in thin layers 
a straw-yellow, in thicker layers an orange-yellow. In polarized light one of the most 
beautiful examples of polychroism is observed by looking across the faces 010. the coloiu- 
passing in the case of thin layers from a pure yellow to a deep red. But even in ordinary 
light the polychroism is perceptible ; for the light passes with a riolet-red through the 
faces 10 0, and with an orange-red colour of far less intensity through the faces 010. 
Hardness less than that of gypsum.” 
The red crystals appear to possess the character of a weak base. They dissolve in 
strong hydrochloric acid, forming a colourless liquid, from which potassa or ammonia 
throws down the compound in its original state, though somewhat lighter in colour, on 
account of its minute state of division. The acid solution forms 'srith dichloride of 
platinum a light yellow amorphous salt, insoluble in alcohol and ether, which changes 
colour and somewhat decomposes on drying. It darkens in colour, even when diled 
at the common temperature in vacuo^ hydrochloric acid fumes being evolved. The 
analysis of two different preparations gave the following results : — 
0-7263 grin, platinum salt, treated with carbonate of sodium, &c., gave 0-1SS5 grin. 
= 25-95 per cent, of platinum, and 0-7450 grm. of chloride of silver =25-37 per cent, 
of chlorine. 
In a second determination, 0-1900 grm. of platiiiiini-salt, analysed in the same manner, 
gave 0-200 grm. of chloride of silver =26-04 per cent, of chlorine. 
The formula 
(G^Hg).,?, CS,, HCl, PtCfr 
requires 24-66 per cent, of platinum and 26-61 per cent, of chlorine. 
The gold-salt is obtained like the platinum-salt, and exhibits similar properties. This 
salt is not better adapted for analysis. 
It is not very easy to form a clear notion of the constitution of the red crystals. 
According to the formula, the compound is the primary triethylphosphoniuni-salt of 
siilphccarbonic acid minus 1 eqiiiv. of sulphuretted hydrogen, and corresponds therefore 
