29 
The oxidizing process which has taken place in this in- 
stance may be expressed by the formula: 
3CaO, P0 5 , S0 2 , 2 HO + 0 = 2CaO, HO, P0 5 + CaO, S0 3 + HO. 
The original substance contained 34'5 per cent. P0 5 and 
15-8 per cent. Sulphurous Acid, equal to 19 '75 per cent. S0 3 . 
The sample for the last analysis ought therefore to contain 
for 24*58 per cent. P0 5 , 14 per cent. S0 3 , but according to 
the analysis it contains 18*59 per cent., that is 4J per cent, 
more. This excess of Sulphuric Acid proves that it is dis- 
solved at a slower rate than the Phosphoric Acid. Calcu- 
lating the amount of Lime which the acids of the analysis 
require, we find for 
18*59 S0 3 as CaO, S0 3 13 '01 per cent. CaO 
and for 
24*58 per cent. P0 5 as 2CaO, P0 5 ... 19*28 „ ,, 
Total 32 '29- per cent. 
This number is less than the quantity of CaO found, by 1*37 
per cent., which excess is to be accounted for by the ten- 
dencies of the Dibasic Phosphate to undergo a partial de- 
composition under the action of water, in consequence of 
which a compound of higher basicity is left undissolved. 
It is therefore evident that the new compound will, in 
the soil, act as a soluble Phosphate of Lime. It has in 
fact for several seasons been used as Manure, and has given 
great satisfaction. 
Strong mineral acids dissolve the Sulphited Phosphate of 
Lime under effervescence of Sulphurous Acid. Acetic Acid 
has no effect in the cold, and dissolves it only after long con- 
tinued boiling, but much easier when the air has access. 
Oxalic Acid decomposes it a little quicker. Chlorine gas is 
readily absorbed by the new Phosphate. After the action 
is completed it contains no more Sulphurous Acid, but only 
traces of Sulphuric Acid. Of the Phosphoric Acid only a 
small portion has become soluble (about 1-X2th). This de- 
composition still occupies my attention. 
