8. Test for the presence of lime
The clay to be tested has to be taken out from the bulk supply by ‘Cone and Quarter’ method - the sample to be prepared is around 1 kg. From this master sample take out about 100 gms and soak it in distilled water about 1 litre. After soaking, stir it for few minutes and leave the sample overnight.
- Pipette out 100ml of the sample into a flask
- Add 10 ml of buffer solution and 1 tablet of Total hardness indicator
- Titrate with E.D.T.A solution until the colour changes from red to blue.
- Express as CaCO3 by calculating the consumption of E.D.T.A required for titration.
