394 J. P. Cooke—Argento-Antimonious Tartrate. 
of silver emetic in water like that of cream of tartar and other 
salts of tartaric acid is very greatly increased by heat, and we 
were easily able to obtain good crystals of the compound in 
arge quantities by dissolving the precipitate, obtained as 
Wallquist describes, in boiling water, and allowing the solution 
to cool. The crystals are colorless and have a very brilliant, 
almost an adamantine, luster. 
rom the reaction by which silver emetic is formed we 
should infer that the composition of the salt would be ex- 
pressed by the symbol 
Ag, SbO, H, =0,=(C,H,0,) . H,0. 
This compound would theoretically contain 26°34 p. ¢. of silver, 
and, as a mean of three analyses, we obtained for the amount 
of silver in the crystals 26:30 per cent, as previously stated. 
The crystals of silver emetic rapidly blacken in the light and 
are very easily decomposed by heat. This decomposition takes 
place at about 200° C. with a slight explosion. A very fine 
carbon dust is blown out of the crucible and a residue is left 
ind, which under the microscope 1s 
seen to consist of spangles of metallic 
silver mixed with an amorphous powder. 
Almost the whole of the powder dissolved 
easily in a solution of tartaric acid, and 
100 110 it evidently consisted of Sb,0,. In one 
experiment we weighed the silver emetic 
and the product, and found that 0-8460 
gram. of the salt left 0°5304 gram. of rest- 
due. If the residue consisted solely of 
/ silver and Sb,O,, theory would require 
05200 grams, and it can be seen from this 
how perfect the decomposition was. 1t 
is obvious therefore that were this compound occluded as we 
at first feared, it would have made itself evident on drying the 
precipitates. 
Mr. W. H. Melville, assistant in this laboratory, has made 
the following crystallographic measurements of the erystals 
whose formation and reactions we have described. 
Angles between normals. 
(111) A, (100) = 70-194’ 
Qi) A: Qh): Fear 
O20 es) 1960 +0571 
IL. Measured. 
100: 136 54° 192’ 54° 10’ 
111 /A\ 110 54° 51' 54° «254 
The pinacoid planes were irregular and the angles can only 
be regarded as approximate. 
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