ON THE TARTRATE OF IRON AND AMMONIA. 277 
less a bicarbonate, which contains much less of the volatile 
alkali than the sesqui-salt. 
In case the crystalline carbonate is not at hand, take half 
the tartaric acid, saturate it with the ammoniacal carbonate, in 
whatever state it may be, and then add the remainder of the 
acid. 
When the quantity prepared is small, and the evaporating 
vessel is shallow, the salt is obtained in brilliant scales of a 
dark brown color in mass; but when held between the eye 
and the light, a beautiful garnet hue. When, however, the 
quantity is considerable, it presents the form of angular grains 
resembling kino. Its powder has a brown color, like iron 
rust. It is very soluble in water, requiring rather more than 
its weight of that fluid at 60° Fahr. for complete solution; but 
to effect this, it is necessary that they be in contact for many 
hours. When a solution of this tartrate is boiled, no change 
takes place, and it is consequently more stable than the tar- 
trate of iron and potassa. Like that last named, this salt is 
insoluble in anhydrous alcohol, and is precipitated from its 
aqueous solution by it of a dull yellow color. It is totally in- 
soluble in ether, the grains not even agglutinating together 
when mixed with it. 
Notwithstanding an approximative idea may be formed of 
the composition of tartrate of iron and ammonia, from its syn- 
thesis, yet to ascertain more definitely its composition, as re- 
gards the water and sesqui-oxide of iron it contains when 
made by the foregoing formula, the following experiments 
have been made. 
One hundred parts of the salt, in powder, contained in a 
capsule surrounded by warm sand, was placed in vacuo over 
a surface of sulphuric acid, until it ceased to lose weight, 
which required nearly three days. The loss, by this treat- 
ment, was 15.7 parts, which is more than four equivalents of 
water. It is evident, however, from the character of the salt 
and process, that the amount of water it contains, depends 
much on the length of time the heat is applied in its evapora- 
tion. 
