The further treatment of the solution is modified according to these circumstances. _a._ THE ALKALOID IS LIQUID AND VOLATILE. If, upon the evaporation of the ether, oily streaks were left on the watch-glass, a volatile alkaloid is probably present. In this case, a solution of caustic potassa is added to the test-tube, the mixture shaken, the supernatant ether decanted[M] into a flask and the remaining solution again washed with ether until the last portion fails to leave a residue upon evaporation. The etherial fluids are then united, and two cubic centimetres of water, acidulated with one-fifth of its weight of sulphuric acid, added. This acid retains the alkaloid, which is now in the state of a pure acid-sulphate soluble in water, the animal matters present remaining dissolved in the ether. The ether, in which some sulphate of conia may be contained--although the greater portion of this compound would remain in the aqueous solution--is then decanted. The remaining aqueous solution of the pure sulphate of the alkaloid is placed in a test-tube, a solution of caustic potassa and some ether added, and the mixture well shaken. The ether is next decanted and allowed to spontaneously evaporate in a dry place at a very low temperature, and the ammonia possibly present is then removed by placing the vessel containing the residue over sulphuric acid. The residue now obtained consists of the alkaloid present in a state of purity, and can be directly identified by means of the reactions described further on. [M] The necessity of decanting etherial and other solutions is advantageously obviated by the use of a pipette.--_Trans._ _b._ THE ALKALOID IS SOLID.