Determining slaking nature of lime

The slaking nature is a field test of the lime class.

1. Take a small lump of quicklime in a container and add water.
2. Observe the reaction.
   • Fat lime: slakes quickly and violently, producing great heat and steam, swelling to 2 to 2.5 times its volume and forming a fine white paste.
   • Hydraulic lime: slakes slowly with little heat and little swelling and leaves a gritty residue.
   • Poor lime: hardly slakes and gives little heat.

The time taken and the heat evolved, together with the volume expansion, show the nature of the lime. A thermometer can record the maximum temperature rise.