Into pernitrate of iron, there is no lasting precipitation, till about 
Seyen-eighths of the acid is combined with ammonia. There is a 
slight opacity induced, even at an early stage of the process, but 
the liquid becomes quite clear again by standing some hours 
each addition of ammonia. The nitrates of chrome and alumina 
bear less ammonia, but the opacity disappears in a much shorter 
ume. The chlorids behave very much like the nitrates. In 
_ analyzing crystals of hydrated chlorid of iron—Fes Olz He—by 
means of carbonate of baryta, at least three-fourths of the acid 
was united with the baryta before any ferric oxyd was de- 
posited. The sulphates of iron, chrome, and alumina allow half 
their acid to be neutralized with ammonia, and the liquid in each 
itself perfectly in a few moments. 
gard to common alum, this property has long been 
~ Own, as well as the fact that the pure sesquibasic sulphates of 
iron, alumina, and chrome, and the bibasic sulphates of zirconia 
and glucina, are soluble and uncrystallizable. It will be seen 
. from What follows, that it generally requires far more of sulphu- 
“ot of most others, to keep the sesquioxyds in solution. 
Me. 
; acid it is one of the weakest of the bases, and among all the 
7 co. 
cm is nothing for a part of the newly formed base to com 
ine with, ; ae 
, But it should be noticed that ferric oxyd exhibits quite dis- 
tnetly the power of existing in two states,—being, in the one, 
oF euscePtible of combination, and, in the other, almost cotta 
state t td by a stosalt oxydizing in the 
: nanieea an pe kta ae extent to which they 
ee : : i eS i Lee en en 
- Stams of the crystallized nitrate of iron boiled with about 800 
-Btams of water, gave a light brown precipitate and a liquid 
st colorless when cold. ‘The liquid contained all the acid and 
of the iron. The rusty precipitate subsided without 
