448 MEDICAL JURISPRUDENCE 1. Petroleum ether to extract picric acid, salicylic acid, benzoic acid, camphor, ethereal oils, capsicin, piperine and the esters of salicylic and benzoic acids with guaiacol, naphthol and cresol. 2. Benzene to extract caffeine, veratrine, hydrastine, piperine, cantha- ridin, santonin, colocynthin, digitalin, absinthin, elaterin and resorcin. 3. Chloroform to extract theobromine, colchicine, papaverine, narceine, hydrastine, cinchonine, cinchonidine, jervine, acetanilide, picrotoxin, gelsemic acid, helleborin, etc. The acid solution is now shaken up with petroleum ether to remove traces of chloroform. It is then rendered slightly alkaline by the cautious addition of ammonia, and the following solvents are added successively to separate the undermentioned substances : — - 1. Petroleum ether to dissolve out volatile alkaloids and aniline, as also strychnine, brucine, coniine, nicotine, lobeline, quinine, veratrine, pyridine, aconitine/gelsemine, etc. 2. Benzene to dissolve out strychnine, brucine, cocaine, atropine, hyoscyamine, hyoscine, veratrine, codeine, narcotine, thebaine, apomorphine, physostigmine, etc. 3. Chloroform to dissolve out berberine, cinchonine, narceine, papa- verine, and traces of morphine. 4. Amyl alcohol to dissolve out morphine, solanine, salicin and traces of saponin, narceine, etc., that may have been still left in the alkaline solution. 5. The remaining portion of the alkaline solution is evaporated to dryness with the addition of powdered glass and the residue is extracted with chloroform, when curarine will separate out. In order to obtain quicker and better results Webster 12 recommends the use of a perforator instead of shaking out with the immiscible solvents. The solvent is automatically and continuously carried through the aqueous liquid contained in the perforator, which is of two forms — one to be used with liquids, such as ether, which are lighter than water, and another to be employed with liquids, such as chloroform, which are heavier than water. General Tests for Alkaloids. — 1. Wagner's Reagent. — Iodine dissolved in a solution of iodide of potassium gives a reddish-brown precipitate, if added to most alkaloids. 2. Mayer's Reagent. — Biniodide of mercury gives a yellowish-white crystalline precipitate with an acid solution of most alkaloids. Biniodide of mercury is prepared by adding a solution of iodide of potassium to one of mercuric chloride, when a scarlet precipitate is f ormedy which is just dis- •solved by a further addition of either of the two. ' f 3. Sonnenschein's Reagent— Phosphoinolybdic acid giyesr a yeUow amorphous precipitate with most Alkaloids. 4. Scheibler*$ Reagent — Ph<i«photpngstic acid has the same reaction as No. 3. 5. Pldttnte CMorick.^-A solution of platiBfe Chloride gives a brown precipitate with alkaloids. * 6. Tannin, Picric Acid or Mercuric .Chloride.— :E?tch. of these, when added to alkaloids, precipitates them, Metallic P^^s^Ew» methods, „ viz^ wet and ctcy^ %£& emplo^eelior extracting metalM^pois«s from orgai^TfiiSdioi^. V , Batpk W. Webster, Legal MeA <md Toxw3©i<w, B3^ & 346.