<PICT:0645876/IV (b)/1> The extraction of organic substances, e.g. alkaloids, in solution in one solvent is effected by another solvent, the two liquids being separated by a membrane which is permeable to the substance but not to more than one of the solvents and is insoluble in both solvents under the conditions of operation.  If the two solvents are miscible, as in the case of water of different pH values, the membrane is impermeable to both liquids.  If the solvents are immiscible and the membrane is permeable to one solvent only, an excess pressure is maintained on the second solvent in order to prevent the first solvent from penetrating the membrane.  The membrane, which may be in tubular or sheet form and supported if desired, is saturated either with water (hydrophilic) or with a water immiscible solvent (hydrophobic) and may be made from parchment paper, agar-agar, rubber or polyvinyl chloride.  A preferred membrane is one of polyvinyl chloride made by passing a fabric through a hot solution of the polymer, the membrane being saturated with a suitable solvent such as chloroform, chlorobenzene, o-dichlorobenzene and amyl acetate or a blend of solvents which swell the membrane to a suitable degree.  The process may be employed for the separation of two organic substances, e.g. hyoscine from hyoscyamine, by countercurrent extraction fractionation, or for the separation of crystal-line substances from resinous bodies of otherwise similar chemical structure, as for example, atropine and belladonnine.  As applied to the extraction of hyoscine and hyoscyamine (including atropine) from an alkaline aqueous solution of hyoscyamus muticus, a polyvinyl chloride tubular membrane 1 is employed.  The membrane is enclosed by a spaced glass tube 2, the aqueous liquids passing through the space between the glass and the membrane and the immiscible solvent passing countercurrently inside the tubular membrane.  An excess pressure is maintained on the aqueous liquid. In stage 1, the aqueous alkaline solution flows into tube 2 through pipe 3 and the alkaloids are extracted by a solvent, e.g. chloroform or chlorobenzene flowing countercurrently through pipe 4.  In stage 2 the alkaloids are extracted from the solvent in pipe 4 by N/10 sulphuric acid flowing countercurrently through entry 5 into tube 2; Substage A strips the fluid issuing at outlet 7 of hyoscyamine which is returned to stage 2 in solution in the solvent.  Substage B strips the fluid issuing at outlet 6 of hyoscine which is returned to the appropriate place in stage 2. A solution of the salts of volatile bases with some hyoscyamine sulphate is obtained from outlet 10, a solution of pure hyoscyamine sulphate from outlet 11 and a solution of hyoscine sulphate mixed with some hyoscyamine from outlet 8.ALSO:<PICT:0645876/III/1> The extraction of organic substances, e.g. alkaloids, in solution in one solvent is effected by another solvent, the two liquids being separated by a membrane which is permeable to the substance but not to more than one of the solvents and is insoluble in both solvents under the conditions of operation. If the two solvents are miscible, as in the case of water of different pH values, the membrane is impermeable to both liquids.  If the solvents are immiscible and the membrane is permeable to one solvent only, an excess pressure is maintained on the second solvent in order to prevent the first solvent from penetrating the membrane. The membrane, which may be in tubular or sheet form and supported if desired, is saturated either with water (hydrophilic) or with a water-immiscible solvent (hydrophobic) and may be made from parchment paper, agar-agar, rubber or polyvinyl chloride.  A preferred membrane is one of polyvinyl chloride made by passing a fabric through a hot solution of the polymer, the membrane being saturated with a suitable solvent such as chloroform, chlorobenzene, o-dichlorobenzene and amyl acetate or a blend of solvents which swell the membrane to a suitable degree.  The process may be employed for the separation of two organic substances, e.g. hyoscine from hyoscyamine, by counter-current extractive fractionation, or for the separation of crystalline substances from resinous bodies of otherwise similar chemical structure, as, for example, atropine and belladonnine.  As applied to the extraction of hyoscine and hyoscyamine (including atropine) from an alkaline aqueous solution of hyoscyamus muticus, a polyvinyl chloride tubular membrane 1 is employed.  The membrane is enclosed by a spaced glass tube 2, the aqueous liquids passing through the space between the glass and the membrane and the immiscible solvent passing countercurrently inside the tubular membrane.  An excess pressure is maintained on the aqueous liquid. In stage 1, the aqueous alkaline solution flows into tube 2 through pipe 3 and the alkaloids are extracted by a solvent, e.g. chloroform or chlorobenzene flowing countercurrently through pipe 4.  In stage 2 the alkaloids are extracted from the solvent in pipe 4 by N/10 sulphuric acid flowing countercurrently through entry 5 into tube 2. Substage A strips the fluid issuing at outlet 7 of hyoscyamine which is returned to stage 2 in solution in the solvent.  Substage B strips the fluid issuing at outlet 6 of hyoscine which is returned to the appropriate place in stage 2.  A solution of the salts of volatile bases with some hyoscyamine sulphate is obtained from outlet 10, a solution of pure hyoscyamine sulphate from outlet 11 and a solution of hyoscine sulphate mixed with some hyoscyamine from outlet 8.