ue | 35.38 | 25.94 | 50.40 |
| Alumina (Al2O3) | / 19.80 | / 22.74 | 13.86 |
| Ferric oxide (Fe2O3) | \ | \ | 3.10 |
| Lime (CaO) | 5.68 | 4.06 | . . |
| Magnesia (MgO) | 0.35 | 1.37 | 0.13 |
| Sulphuric anhydride (SO3) | Trace | Trace | . . |
| Combined water (H2O) | / 4.27 | / 8.92 | 7.57 |
| Carbonic anhydride (CO2) | \ | \ | . . |
| Moisture | . . | . . | 5.04 |
| Alkalis and loss | 6.72 | 4.33 | 0.58 |
| +-----------+-----------+-----------+
| | 100.00 | 100.00 | 100.0 |
+-----------------------------+-----------+-----------+-----------+

An artificial product which serves perfectly as a pozzuolana is
granulated blast-furnace slag. The slag, which must contain a high
percentage of lime, is granulated by being run while fused into
abundance of water. This granulated slag differs from the same slag
allowed to cool slowly, in that a portion of the energy which it
possesses while fused is retained after it has solidified. It bears to
ordinary slowly-cooled slag a similar relation to that borne by plastic
sulphur to ordinary crystalline sulphur. This potential energy becomes
kinetic when the slag is brought into contact with lime in the presence
of water, and causes the formation of a true hydraulic silicate of lime.
The following analysis shows the composition of a typical slag:--

Per Cent.
Insoluble residue 1.04
Silica (SiO2) 31.50
Alumina (Al2O3) 18.56
Manganous oxide (MnO) 0.44
Lime (CaO) 42.22
Magnesia (MgO) 3.18
Soda (Na2O) 0.70
Sulphuric anhydride (SO3) 0.45
Sulphur (S) 2.21
------
100.30
Deduct oxygen equivalent to sulphur 1.10
------
99.20

Granulated slag of this character is ground with slaked lime until both
materials are in a state of fine division and intimatel