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SELECTED ARTICLES. 
when each operation gave to us salts of different composi- 
tions. 
Tartrate of Boron and Potassa. 
The tartrate of boron and potassa, (soluble cream of tartar,) 
when perfectly saturated with boracic acid, has a composition 
corresponding to that of tartar emetic, and of the tartrate of 
iron and potassa dried at 100° c. The oxygen of the boracic 
acid is three times the oxygen of the potassa. But as we can have 
but little fear that a ready reduction of the boracic acid should 
confine our experiments, we have examined whether the so- 
luble cream of tartar is affected by heat in the same manner 
as tartar emetic. We soon ascertained that we could raise 
the temperature to 285° c. without producing any change. It 
remained, after this experiment, equally as soluble in water 
as previous to the action of the heat. 
First Experiment. 
5£ r ,642 of soluble cream of tartar dried at 100° c, and 
afterwards heated to 280°, lost- 
Water, 0.464 gr., or 8.227 p. 100. 
Second Experiment. 
3 gr ,535 of another specimen lost — 
Water, 0.285 gr., or 8.06 p. 100. 
Third Experiment. 
2 gl ',872 of a third specimen lost — 
Water, 0.230 gr., or 8.008 p. 100. 
Admitting that the loss for soluble cream of tartar ought to 
be, as for tartar emetic, of two equivalents of water, the theo- 
retic loss should be 8.37 p. 100, and the soluble cream of 
tartar under these circumstances may be fully assimilated 
with tartar emetic. 
We would willingly avail ourselves of other information 
from analogous tartrates. It would be a matter of curiosity 
