When the distribution is small, we have to carry out the multiple extractions. But multiple extraction brings no. of the complications and is very tedious. Kutcher and Steudel devised a continuous extractions to avoid the multiple extractions.
1. When the extracting solvent is heavier than water (aqueous). It is consist of tube and reservoir. The reservoir contain the same organic solvent. The tube is fitted with the condenser. The solvent in reservoir is heated slowly which is converted into vapours, Which move up and are condensed and the organic solvent is converted into liquid which is heavy and descend while moving through aqueous, the solute gets transferred from aqueous to organic and at the bottom we get solution of solute in organic. so the level increases and corresponding solution will fall in reservoir. This continue till maximum amount of solute is transferred from aqueous to organic. Then by opening the stopper at the bottom, we can separate organic and aqueous layer, then solute can be extracted from organic.
2. When organic solvent is lighter than aqueous. In that case reservoir contain organic, which on warming is converted into to the vapours, which ascends and is condensed in condenser which descends through bubbler type of funnel. This liquids goes to bottom but as it is light so it ascends, and passes through solution and here the solute gets transferred from aqueous solution. So the level of of the solution increases and the corresponding gets transferred to reservoir.
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