Magnesic meta-phosphate MgO.P2O5.
Magnesic pyro-phosphate 2MgO.P2O5.
Magnesic ortho-phosphate 3MgO.P2O5.
[109] The composition of which is—
MoO2 90.74,
P2O5 3.14,
(NH4)2O 3.57,
H2O 2.55=100.00.
[110] This is made by adding 27 grams of magnesium carbonate (a little at a time) to a solution of 270 grams of citric acid in 350 c.c. of warm water; and, when dissolved, adding 400 c.c. of dilute ammonia, and making up the bulk to 1 litre; 20 c.c. of the solution is sufficient for 0.1 gram of P2O5, although more will be required if much iron or alumina is present.
[111] For the details of the titration, the student is referred to the same place.
[112] N2O5 + 6FeO = 3Fe2O3 + 2NO.