Objective: The purpose of this demonstration is to determine the viability of an aggregate based on the amount of organic matter present.
The color of the liquid will indicate whether or not the aggregate contains too much organic matter. A colorless liquid indicates a clean aggregate, free from organic matter. A straw-colored solution, not darker than apple-cider vinegar, indicates some organic matter bur not enough to be seriously objectionable. Darker colors mean that it contains too much organic matter and should not be used unless it is washed and tested again.
The sand leaves a colorless liquid. The sand-dirt mixture produces a yellow to orange liquid.