A general method for effecting the detection of alkaloids was first proposed by _Stas_. Since the publication of this method, modifications to it have been recommended by _Otto_, and by _L. Uslar_ and _J. Erdman_. Other processes have been suggested by _Rodgers_ and _Girwood_, by _E. Prollius_, and by _Graham_ and _Hofman_. The latter will doubtless become general in their application; but up to the present time they have been employed exclusively in the detection of strychnine. Dialysis has also been recently applied in the separation of alkaloids. [L] Colchicine, picrotoxine and digitaline. STAS'S METHOD. This method is based upon the facts: (_a_), that the acid salts of the alkaloids, especially those containing an excess of tartaric or oxalic acids, are decomposed by caustic alkalies and by the bicarbonates of soda and potassa; (_b_), that the alkaloids, when liberated in this manner, are combined with a certain amount of water which determines their solution in ether, although, in a desiccated state they may be insoluble in this menstruum; (_c_), that they may be extracted from their aqueous solutions by agitation with ether. Stas's original method is as follows: The suspected substances, if organs are contained, are cut into fine shreds, then mixed with absolute alcohol, 0.5 to 2. grammes of tartaric or oxalic acid added and the whole introduced into a flask and heated at a temperature of 60° to 75°. When quite cold, the mixture is filtered, and the undissolved portion remaining on the filter washed with absolute alcohol, the washings being added to the filtrate. The alcoholic solution is evaporated, either by placing it under a bell-jar connected with an air-pump, or by passing a current of air, having a temperature not exceeding 35° over it, until reduced to a quarter of its original volume: the complete expulsion of the alcohol being then rendered certain. If insoluble matter separates during this operation, the concentrated fluid is passed through a moistened filter, the water used in washing the residue being united to the filtrate which is then evaporated to dryness by aid of the air-pump or by placing the fluid in a bell-jar over concentrated sulphuric acid. When the evaporation is completed, the residue is treated with absolute alcohol, the alcohol allowed to evaporate at the ordinary temperature of the air, and the second residue dissolved in the smallest possible amount of water. The fluid thus obtained is placed in a test-tube, and a concentrated solution of bicarbonate of soda added so long as effervescence takes place. Ether is then added, the mixture thoroughly shaken, and after it has remained at rest for some time, a small portion of the supernatant ether removed and evaporated on a watch-glass: the residue obtained will consist of the alkaloid present. Two cases are now possible: the alkaloid is a solid, or it is a liquid and is volatile.