1903.] KOENIG—ARTIFICIAL PRODUCTION OF CRYSTALS. 233 
The analysis reveals two points: 1. Arsenic does not add itself 
to a ready-formed molecule Cu,Sb. The same preferential attrac- 
tion towards copper comes into play as in the case of the metallic 
constituents of copper alldys. The ionic mobility of antimony is 
low; at any rate, at the low temperature in use during this 
experiment. 2. The ratio indicates that antimony is probably 
merely mechanically carried along so long as copper is at hand 
for the arsenic; for if antimony be considered out of the mole- 
cule the ratio will be Cu: As= 2.82: 1.00. But even this is 
unsatisfactory for a crystallized body with no mechanical admix- 
ture likely, for the crystals were all separate and large enough to 
be fully scrutinized. 
For more light I went to examine into the material directly under 
and back of the large crystals. This material is loose, in small 
loose grains of angular habitus, not scaly at all, as the large crys- 
tals. Habitus quite unlike that of the domeykite ; color darker gray. 
The analysis of this material (0.0570 gram) gives: 
CuO = 0.0393 Chesed Awe) 03 0 08800 
Sb,S, = 0.0028 Sb 92/53 2 122.0028, 
As,S, = 0.0480 AS'== 401665"): 175 0.5421 t ar 
99.61 
Ratio: 
Cal CASSb)) — Ssor57 0 —-3 Ooi. 2 
As the copper becomes scarce, the arsenic being still plentiful, 
this new 3/2 molecule forms. In spite of the superabundance of 
antimony, the selection of copper continues. With nickel we saw 
in similar conditions the forming of 2/1 molecule. The affinity 
for antimony is quite low, and yet it is probably the influence of 
the Jatter through which 3/2 and not 2/1 are brought into being. 
The excess of arsenic in the large crystals accounts for itself by 
the presence of this 3/2 molecule under the influence of antimony. 
Lxperiment of February 4, rgoz.—The same alloy Cu,Sb was ex- 
posed for thirty-six hours at a higher temperature, about 550° C. 
Two products were obtained. Forward, towards the arsenic, a lus- 
trous gray mass, apparently of fused crystals. The outermost part 
of this mass was broken off, revealing a hollow center, an inner 
layer of dark-gray mass, an outer layer of lighter color. Could not 
separate the two. Let this be material (a). The second substance 
