This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
"After the exhaustion of the powder has been accomplished, the absorbed alcohol may be recovered by distillation with steam, or, when this is impracticable, it may be obtained by percolation with a weaker alcohol, the alcoholic strength being gradually reduced until finally water is used for pushing the last portions of the percolate through. The more mucilaginous the material is, the greater the caution which should be exercised in this decrease of the alcoholic strength. The alcohol thus obtained requires to be rectified, and may usually be deprived of its foreign odor by distillation, with a small quantity of potassium permanganate".- N. D.
It should be made a rule, no matter what the menstruum is, never to attempt to displace it from the drug with water or with any other menstruum, before the whole amount of fluid extract and reserves are collected. The menstruum finally left in the drug may then be displaced by water, if possible. If it was alcohol, and the drug resinous, this will be easy. The best way is to transfer the whole residue to a still, and distil off all the volatile liquid. In manufacturing establishments, stills of special construction are kept for such purposes. Those who work on a small scale will sometimes find it more economical to throw away a residue than to attempt to extract the menstruum.