Carefully remove 2 mL of saturated KCl solution (at 50 C°) above the undissolved solids by a pipette (avoid the undissolved solids enter into the pipette ) and quickly drain into a 50 mL beaker. Wait to attain room temperature and weigh the 2 mL of saturated KCl solution (it does not matter if solid KCl may be occurred before weighing). Transfer into a 250 mL volumetric flask and dilute to volume with distilled water. Repeat this step but change temperatures in step 4 to 40 °C, 30 °C and 20 °C, respectively.