a vertical tube or column attached to a still and usually filled with packing, eg Raschig rings, or intersected with b8ubble plates. An internal reflux takes place, resulting in a gradual separation between the high- and the low-boiling fractions inside the column, whereby the fractions with the lowest boiling point distil over. The efficiency of the column depends on its length or the number of bubble plates used, and also on the ability of the packing to promote contact between the vapour and liquid phases., seade rektifikatsiooni teostamiseks, rektifikatsioon - mitmeastmeline, korduv destilleerimine