1, pour clean water into the same clean beaker, and then take a spoonful of coarse salt into the beaker with a medicinal spoon, stirring with a glass rod to accelerate the dissolution, and then add the coarse salt, stirring with a glass rod until the addition of the coarse salt until the coarse salt does not dissolve and then stop.

2. Add excess barium chloride, sodium hydroxide and sodium carbonate to remove soluble impurities from the crude salt.

3, the filter paper will be folded twice into the funnel, and a small amount of distilled water to wet the filter paper so that the filter paper tightly in the funnel after the funnel into the funnel into the iron frame table, the funnel placed at the lower end of the beaker should be placed close to the wall of the liquid to receive.

4, the beaker containing crude salt to remove soluble impurities leaned on a glass rod into the funnel, the lower end of the glass rod to lean on the thickest side of the filter paper. The height of the coarse salt water in the funnel should not exceed the height of the filter paper. If the filtrate remains cloudy this operation can be repeated until the filtrate is clarified.

5, the funnel will be added to distilled water to soak the precipitation and let stand, so that the water is filtered out, repeat the operation twice will be poured into the just filtered demineralized water.

6, the evaporating dish placed on the iron frame table, the filtrate will be poured into the evaporating dish, the amount poured into not less than one-third nor more than two-thirds. Use an alcohol lamp to heat, always use a glass rod to stir during the heating process. Stop heating until the liquid runs out and use the residual heat to evaporate the filtrate. This process still need to use the glass rod stirring.

7, waiting for the evaporation dish cooling, with a glass rod to transfer the crystals out, these crystals are seawater boiled salt purified salt.