ON THE TARTRATE OF IRON AND POTASSA. 
191 
than an occasional agitation of the mixture in the interior ves- 
sel. Indeed in one instance the process was left in operation 
for seven hours, without the thermometer having risen higher 
than the required temperature, thus showing that what ap- 
pears to be a troublesome piece of manipulation, is really very- 
simple and easy. According to Soubeiran and Capitaine, 
the composition of the salt, when thus prepared, is as follows: 
1 atom Sesquioxide of Iron, 80=30.77 
1 " Potassa, 47=18.07 
2 « Tartaric acid,* 133 = 51.16 
1 " Tart, of Iron and Potassa, 260=100.00. 
In this it is evident that the oxygen in the oxide of iron is 
to that in the potassa as 3 to 1. In the salt thus prepared there 
is forty per cent, more iron than in that previously described. 
Its color is dark brown, but when held in laminated pieces, 
between the eye and the light, it is ruby-red; it is perfectly 
soluble in water, with which it forms a dark brown transpa- 
rent solution, and requires about four times its weight of that 
fluid at 60°, for solution. When this saturated solution is boiled 
it deposits a black matter, which is owing, according to Soubei- 
ran and Capitaine, to the reduction of some of the oxide of 
Iron and the consequent decomposition of a portion of the 
salt. This preparation has less of the peculiar inky taste of 
ferruginous salts, than many of the compounds of iron; it con- 
tains thirty'per cent, of sesquioxide of iron, and undoubtedly 
is one of the best preparations of this class. Like tartrate of 
antimony and potassa, this salt, is precipitated from its 
aqueous solution by an excess of alcohol, and in the form of a 
brownish yellow colored powder, which is as soluble as be- 
fore. Owing to its insolubilily in alcoholic menstruua, it is 
necessary to dilute wine before it will take up sufficient to 
make a wine of iron of sufficient strength. One part of 
Madeira wine and as much water will dissolve about l-21st of 
its weight of the salt, which is about a scruple to the ounce. 
*The atom of tartaric acid in the paper of Soubeiran and Capitaine be- 
fore alluded to, represents two, according to Turner. 
