122 J. P. Cooke—Atomie Weight of Antimony. 
from an unusually concentrated solution of antimonious chloride 
in tartaric acid, and had stood over night, our attention was 
called to some crystalline grains, which, on examination, proved 
to be a compound of tartaric acid, antimony and silver. We 
soon found that this product could be readily obtained by 
concentrating the filtrate from the precipitate of argentic 
chloride, and adding to it, while still warm, an excess of 
argentic nitrate. On coo ing, the new crystals form in abun- 
d hey have not yet been measured, but under the 
microscope they have the general aspect of right rhombic plates 
or prisms, with hemihedral modifications,—a general form which 
is so characteristic of the tartrates, and which we ourselves 
have previously studied in our crystallographic determinations 
of the tartrates of rubidium and cesium.* We obtained for 
the amount of silver in the acca as a mean of three analyses, 
26°30 per cent. The compound Ag, SbO.H,=0,=(C, 
H,O would require 26°34 ues cent. “The crystals may there- 
they appear to have prepared the substance only in an amor- 
phous condition. At least, in the description quoted, no men- 
tion is made of any crystalline form. 
These crystals of argento-antimonious tartrate are apparently 
not acted upon in the least by cold water, and only slightly by 
boiling water; and finding this on insoluble material mixed 
with the precipitated chloride of silver, under the conditions 
stated, we were led to fear that “ft might be occluded to some 
extent by this precipitate, even when formed in much more 
dilute solutions of antimony and tartaric acid. The phenom- 
non was very similar to that we had already studied in the 
occlusion of the oxichloride by the sulphide of antimony; and 
there was reason to fear that, as in the previous case, an occlu- 
sion of this double tartrate might canis even when the ale 
t, s] aby tated, w 
had always taken great care not to add more than the slightest 
possible excess of sapie i sikinta, and this was especially true 
in our more recent determinations. Now, however, we were 
* Am. Jour. of Science and Arts, II, xxxvii, 70. 
+ Gmelin Handbook, Cavendish Edition, x, 326. 
