The use of density gradient columns for the comparison of soil samples has been re-examined. It has been shown that reproducible linear gradients, ranging from 1·5 to 2·9g/ml, can be produced in 30cm of glass tubing using bromoform/bromobenzene mixtures. Good reproducibility has also been shown for replicate samples taken from a bulk soil. The variation found for soils of the same dry colour indicates that good discrimination is possible, but not as great as has previously been suggested. An examination of samples from five simulated scenes of crime yielded good reproducibility of density patterns across each of the scenes.
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