56 
PROFESSOR GRAHAM ON THE CONSTITUTION OF 
Theory. 
Experiment. 
One atom peroxide of iron 
. . 1593 
16-13 
Three atoms potash .... 
. . 28-82 
29-07 
Six atoms oxalic acid . . . 
. . 44-25 
43-74 
Six atoms water ..... 
. . 11-00 
10-56 
100- 
99-50 
Hence its composition is the same as that of the preceding salt. 
iron being substituted 
for chromium. 
15. Oxalate of Peroxide of Iron and Soda. 
This salt is formed by dissolving the hydrated peroxide of 
iron in binoxalate of 
soda. It crystallizes in solid green crystals. 
It is composed as follows, the water 
being calculated from the loss on the analysis : 
Theory. 
Experiment. 
One atom peroxide of iron 
. . 16-32 
16-56 
Three atoms soda 
. . 19-57 
19-66 
Six atoms oxalic acid . . . 
. . 45-34 
45-51 
Ten atoms water ..... 
• . 18-77 
18-27 
100 - 100 - 
Of the ten atoms water which this salt contains it readily loses six at 212° Fahr., 
and retains four atoms wafer at that temperature. It differs, therefore, in composi- 
tion, and it does so also in form, from either of the preceding double oxalates. 
A corresponding oxalate of chromium and soda was produced by a similar process, 
and crystallized with some difficulty in solid dark crystals, which appeared to have 
the same form as the preceding soda-salt, and were found, like it, to contain ten atoms 
of water. 
There is also a double oxalate of alumina and potash, which may be made by dis- 
solving hydrated alumina in binoxalate of potash, and crystallizes in white tables of 
a pearly lustre, which have the same form as the oxalate of iron and potash. 
II. Of Nitrates. 
1. Hydrated Nitric Acid, the Nitrate of Water. 
H N li 3 . 
Nitric acid combines with one atom of water as base, and with three atoms more 
by a less powerful affinity. The well-defined character of the combination containing 
four atoms water, which is the acid of specific gravity 1*42, is evinced in its high 
boiling point and in an appearance of saturation which it exhibits. The true and 
complete nitrate of water has therefore three atoms of constitutional water attached 
to it. And in the case of the nitrates of those metallic oxides which correspond with 
