J. P. Cooke—Argento-Antimonious Tartrate. 393 
of the crystals from a few lines to half an inch. The line 
of demarkation between it and the fluo-carbonate is quite 
distinct. This mode of occurrence of the two compounds, 
being such as is often seen in crystals which have undoubtedly 
undergone partial changes of composition, leads to the conclu- 
sion that the bastnisite of Colorado was formed by a change of 
a fluoride into a fluo-carbonate. In the fluoride a distinct but 
not strongly marked cleavage exists parallel to the basal planes 
of the enclosing fluo-carbonate. In the latter we could detect 
no evidence of cleavage. 
Art, LIV.—On Argento-antimonious 7 artrate (Silver Emetic) ; 
by Jostan P. Cooke. (Contributions from the Chemical 
Laboratory of Harvard College). 
As stated by us in our paper on the atomic weight of anti- 
mony,* this compound was originally obtained by Wallquist 
by precipitating nitrate of silver with tartar emetic, and was - 
analyzed both by him and by Dumas and Piria. These chem- 
ists obtained respectively 27°31 and 28°05 per cent of oxide of 
silver. They appear however to have prepared the substance 
only in an amorphous form. As stated in the paper just cited, 
we first noticed the formation of crystals of the compound in a 
concentrated solution of antimonious chloride and tartaric acid, 
ad been added an excess of argentic nitrate, an 
from the circumstances of their formation we were led to form 
a somewhat erroneous inference in regard to their relation to 
water. We find that the substance is far more soluble in this 
product in the precipitation of chlorine, bromine or iodine from 
Solutions of the antimony compounds of these elements in 
tartaric acid, unless the ‘excess of silver nitrate is larger and 
the solutions concentrated ; and although we have most care- 
fully looked for it in the precipitate we have never discovered 
it, except under the peculiar conditions described in our former 
paper, and our fear that it might be occluded by these precip- 
itates was wholly unfounded : i 
It is evident from the above experiments that the solubility 
* This Journal, p. 382, 
