Crude salt purification is through the dissolution of insoluble substances and salt preliminary separation, filtration to completely remove the insoluble substances, evaporation of salt from the solution to separate out the process of salt, the order of operation should be dissolved - filtration - evaporation.

In the dissolution, filtration, evaporation operations are used in the experimental apparatus is a glass rod, the role of the glass rod are stirring, accelerate the rate of dissolution; drainage; stirring, to prevent droplets from splashing.

The answer is: dissolution; filtration; evaporation; glass rod; stirring, accelerate the rate of dissolution; drainage; stirring, to prevent droplet splashing.