PART VI.—ALKALOIDS AND POISONOUS VEGETABLE PRINCIPLES SEPARATED FOR THE MOST PART BY ALCOHOLIC SOLVENTS.

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DIVISION I.—VEGETABLE ALKALOIDS.

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I.—General Methods of Testing and Extracting Alkaloids.

§ 301. General Tests for Alkaloids.—In order to ascertain whether an alkaloid is present or not, a method of extraction must be pursued which, while disposing of fatty matters, salts, &c., shall dissolve as little as possible of foreign substances—such a method, e.g., as the original process of Stas, or one of its modern modifications.

If to the acid aqueous solution finally obtained by this method a dilute solution of soda be added, drop by drop, until it is rendered feebly alkaline, and no precipitate appear, whatever other poisonous plant-constituents may be present, all ordinary alkaloids[324] are absent.

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In addition to this negative test, there are also a number of substances which give well-marked crystalline or amorphous precipitates with alkaloids.

§ 302. These may be called “group reagents.” The chief members of the group-reagents are—Iodine dissolved in hydriodic acid, iodine dissolved in potassic iodide solution, bromine dissolved in potassic bromide solution, hydrargo-potassic iodide, bismuth-potassic iodide, cadmic potassic iodide; the chlorides of gold, of platinum, and mercury; picric acid, gallic acid, tannin, chromate of potash, bichromate of potash, phospho-molybdic acid, phospho-tungstic acid, silico-tungstic acid, and Fröhde’s reagent. It will be useful to make a few general remarks on some of these reagents.

Iodine in hydriodic acid gives either crystalline or amorphous precipitates with nearly all alkaloids; the compound with morphine, for example, is in very definite needles; with dilute solutions of atropine, the precipitate is in the form of minute dots, but the majority of the precipitates are amorphous, and all are more or less coloured.

Iodine dissolved in a solution of potassic iodide gives with alkaloids a reddish or red-brown precipitate, and this in perhaps a greater dilution than almost any reagent. When added to an aqueous solution, the precipitates are amorphous, but if added to an alcoholic solution, certain alkaloids then form crystalline precipitates; this, for example, is the case with berberine and narceine. By treating the precipitate with aqueous sulphurous acid, a sulphate of the alkaloid is formed and hydriodic acid, so that by suitable operations the alkaloid may readily be recovered from this compound. A solution of bromine in potassic bromide solution also gives similar precipitates to the above, but it forms insoluble compounds with phenol, orcin, and other substances.

Mercuric potassic iodide is prepared by decomposing mercuric chloride with potassic iodide in excess. The proportions are 13·546 grms. of mercuric chloride and 49·8 of potassic iodide, and water sufficient to measure, when dissolved, 1 litre. The precipitates from this reagent are white and flocculent; many of them become, on standing, crystalline.

Bismuthic potassic iodide in solution precipitates alkaloids, and the compounds formed are of great insolubility, but it also forms compounds with the various albuminoid bodies.

Chloride of gold forms with the alkaloids compounds, many of which are crystalline, and most admit of utilisation for quantitative determinations. Chloride of gold does not precipitate amides or ammonium compounds, and on this account its value is great. The precipitates are yellow, and after a while are partly decomposed, when the colour is of a reddish-brown.

Platinic chloride also forms precipitates with most of the alkaloids, but since it also precipitates ammonia and potassic salts, it is inferior to gold chloride in utility.

§ 303. (1.) Phosphomolybdic Acid as a Reagent for Alkaloids.—Preparation; Molybdate of ammonia is precipitated by phosphate of soda; and the well-washed yellow precipitate is suspended in water and warmed with carbonate of soda, until it is entirely dissolved. This solution is evaporated to dryness, and the ammonia fully expelled by heating. If the molybdic acid is fairly reduced by this means, it is to be moistened by nitric acid, and the heating repeated. The now dry residue is warmed with water, nitric acid added to strong acid reaction, and the mixture diluted with water, so that 10 parts of the solution contain 1 of the dry salt. The precipitates of the alkaloids are as follows:—

Aniline,	Bright-yellow, flocculent.
Morphine,	Bright„yellow, floc „
Narcotine,	Brownish-yellow, c„
Quinine,	Whitish-yellow, oc„
Cinchonine,	Whitis„yellow, floc„
Codeine,	Brownish-yellow, voluminous.
Strychnine,	White-yellow, w, volum„
Brucine,	Yelk-yellow, flocculent.
Veratrine,	Bright-yellow, oc„
Jervine,	Bright„ yellow, fl„
Aconitine,	Bright„ yellow, fl„
Emetine,	Bright„ yellow, fl„
Theine,	Bright-yellow, voluminous.
Theobromine,	Bright„yellow, volu„
Solanine,	Citron-yellow, pulverulent.
Atropine,	Bright-yellow, flocculent.
Hyoscyamine,	Bright„yellow, floc„
Colchicine,	Orange-yellow,loc „
Delphinine,	Grey-yellow, voluminous.
Berberine,	Dirty-yellow, flocculent.
Coniine,	Bright-yellow, voluminous.
Nicotine,	Bright„yellow, volu„
Piperine,	Brownish-yellow, flocculent.

(2.) Silico-Tungstic Acid as a Reagent for Alkaloids.—Sodium tungstate is boiled with freshly precipitated gelatinous silica. To the solution is added mercurous nitrate, which precipitates the yellow mercurous silico-tungstate. This is filtered, well-washed, and decomposed by an equivalent quantity of hydrochloric acid; silico-tungstic acid then goes into solution, and mercurous chloride (calomel) remains behind. The clear filtrate is evaporated to drive off the excess of hydrochloric acid, and furnishes, on spontaneous evaporation, large, shining, colourless octahedra of silico-tungstic acid, which effloresce in the air, melt at 36°, and are easily soluble in water or alcohol.

This agent produces no insoluble precipitate with any metallic salt. Cæsium and rubidium salts, even in dilute solutions, are precipitated by it; neutral solutions of ammonium chloride give with it a white precipitate, soluble with difficulty in large quantities of water. It precipitates solutions of the salts of quinine, cinchonine, morphine, atropine, &c.; if in extremely dilute solution, an opalescence only is produced: for instance, it has been observed that cinchonine hydrochlorate in ¹⁄₂₀₀₀₀₀, quinia hydrochlorate in ¹⁄₂₀₀₀₀, morphia hydrochlorate in ¹⁄₁₅₂₈₅ dilution, all gave a distinct opalescence.—Archiv der Pharm., Nov., Dr. Richard Godeffroy.

(3.) Scheibler’s Method for Alkaloids: Phospho-Tungstic Acid.—Ordinary commercial sodium tungstate is digested with half its weight of phosphoric acid, specific gravity 1·13, and the whole allowed to stand for some days, when the acid separates in crystals. A solution of these crystals will give a distinct precipitate with the most minute quantities of alkaloids, ¹⁄₂₀₀₀₀₀ of strychnine, and ¹⁄₁₀₀₀₀₀ of quinine. The alkaloid is liberated by digestion with barium hydrate (or calcium hydrate); and if volatile, may be distilled off, if fixed, dissolved out by chloroform. In complex mixtures, colouring-matter may be removed by plumbic acetate, the lead thrown out by SH₂, and concentrated, so as to remove the excess of SH₂.

§ 304. Schulze’s reagent is phospho-antimonic acid. It is prepared by dropping a strong solution of antimony trichloride into a saturated solution of sodic phosphate. The precipitation of the alkaloids is effected by this reagent in a sulphuric acid solution.

§ 305. Dragendorff’s reagent is a solution of potass-bismuth iodide; it is prepared by dissolving bismuth iodide in a hot solution of potassium iodide, and then diluting with an equal volume of iodide of potassium solution. On the addition of an acid solution of an alkaloid, a kermes-red precipitate falls down, which is in many cases crystalline.

Marm’s reagent is a solution of potass-cadmium iodide. It is made on similar principles.

Potass-zinc iodide in solution is also made similarly. The precipitates produced in solutions of narceine and codeine are crystalline and very characteristic.

§ 306. Colour Tests.—Fröhde’s reagent is made by dissolving 1 part of sodic molybdate in 10 parts of strong sulphuric acid; it strikes distinctive colours with many alkaloids.

Mandelin’s reagent is a solution of meta-vanadate of ammonia in mono- or dihydrated sulphuric acid. The strength should be 1 part of the salt to 200 of the acid. This reagent strikes a colour with many alkaloids, and aids to their identification. It is specially useful to supplement and correct other tests. The following table gives the chief colour reactions, with the alkaloids. (See also p. 55 for the spectroscopic appearances of certain of the colour tests.)

METHODS OF SEPARATION.

§ 307. Stas’s Process.—The original method of Stas[325] (afterwards modified by Otto)[326] consisted in extraction of the organic matters by strong alcohol, with the addition of tartaric acid; the filtered solution was then carefully neutralised with soda, and shaken up with ether, the ethereal solution being separated by a pipette. Subsequent chemists proposed chloroform instead of ether,[327] the additional use of amyl-alcohol,[328] and the substitution of acetic, hydrochloric, and sulphuric for tartaric acid.

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COLOUR REACTIONS[329] OF CERTAIN ALKALOIDS.

Name of Substance.	Strong Sulphuric Acid.	Fröhde’s Reagent.	Mandelin’s Reagent.
Strychnine.	...	...	Violet-blue, then lastly cinnabar-red.
Brucine.	Pale red.	Red, then yellow.	Yellow-red to orange, afterwards blood-red.
Curarine.	Fine red.	...	...
Quinine.	...	Greenish.	Weak orange, then blue-green, lastly green-brown.
Atropine.	...	...	Red, then yellow-red, and lastly yellow.
Aconitine.	...	...	...
Veratrine.	Yellow, then orange, blood-red, lastly carmine-red.	Gamboge-yellow, then cherry-red.	Yellow, orange, blood-red, lastly carmine-red.
Morphine.	...	Violet, green, blue-green, and yellow.	Reddish, then blue-violet.
Narcotine.	Yellow, then raspberry colour.	Green, then brown-green, yellow, lastly red.	Cinnabar-red, then carmine-red.
Codeine.	...	Dirty green, then blue, lastly yellow.	Green-blue to blue.
Papaverine.	...	Green, then blue-violet, lastly cherry-red.	Blue-green to blue.
Thebaine.	Blood-red, then yellow-red.	Orange, then colourless.	Red to orange.
Narceine.	Grey-brown, then blood-red.	Brown, green, red, lastly blue.	Violet, then orange.
Nicotine.	...	Yellowish, then red.	Transitory dark colour.
Coniine.	...	Yellow.	...
Colchicine.	Intense yellow.	Yellow to green-yellow.	Blue-green, then brown.
Delphinidine.	Red.	Red-brown.	Red-brown to brown.
Solanine.	Red-yellow, then brown.	Cherry-red, red-brown, yellow, yellow-green.	Yellow-orange, cherry-red, and lastly violet.

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§ 308. Selmi’s Process for Separating Alkaloids.—A method of separating alkaloids from an ethereal solution has been proposed by Selmi.[330] The alcoholic extract of the viscera, acidified and filtered, is evaporated at 65°; the residue taken up with water, filtered, and decolorised by basic acetate of lead. The lead is thrown out by sulphuretted hydrogen; the solution, after concentration, repeatedly extracted with ether; and the ethereal solution saturated with dry CO₂, which generally precipitates some of the alkaloids. The ethereal solution is then poured into clean vessels, and mixed with about half its volume of water, through which a current of CO₂ is passed for twenty minutes; this may cause the precipitation of other alkaloids not thrown down by dry CO₂. If the whole of the alkaloids are not obtained by these means, the solution is dehydrated by agitation with barium oxide, and a solution of tartaric acid in ether is added (care being taken to avoid excess); this throws down any alkaloid still present. The detection of any yet remaining in the viscera is effected by mixing with barium hydrate and a little water, and agitating with purified amylic alcohol; from the alcohol the alkaloids may be subsequently extracted by agitation with very dilute sulphuric acid.

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Another ingenious method (also the suggestion of Selmi) is to treat the organic substance with alcohol, to which a little sulphuric acid has been added, to filter, digest with alcohol, and refilter. The filtrates are united, evaporated down to a smaller bulk, filtered, concentrated to a syrup, alkalised by barium hydrate, and, after the addition of freshly ignited barium oxide and some powdered glass, exhausted with dry ether; the ether filtered, the filtrate digested with lead hydrate; the ethereal solution filtered, evaporated to dryness, and finally again taken up with ether, which, this time, should leave on evaporation the alkaloid almost pure.

§ 309. Dragendorff’s Process.—To Dragendorff we owe an elaborate general method of separation, since it is applicable not only to alkaloids, but to glucosides, and other active principles derived from plants. His process is essentially a combination of those already known, and its distinctive features are the shaking up—(1) of the acid fluid with the solvent, thus removing colouring matters and certain non-alkaloidal principles; and (2) of the same fluid made alkaline. The following is his method in full. It may be advantageously used when the analyst has to search generally for vegetable poison, although it is, of course, far too elaborate for every case; and where, from any circumstance, there is good ground for suspecting the presence of one or two particular alkaloids or poisons, the process may be much shortened and modified.[331]

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I. The substance, in as finely-divided form as possible, is digested for a few hours in water acidified with sulphuric acid, at a temperature of 40° to 50°, and this operation is repeated two or three times, with filtering and pressing of the substances; later, the extracts are united. This treatment (if the temperature mentioned is not exceeded) does not decompose the majority of alkaloids or other active substances; but there are a few (e.g., solanine and colchicine) which would be altered by it; and, if such are suspected, maceration at the common temperature is necessary, with substitution of acetic for sulphuric acid.[332]

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II. The extract is next evaporated until it begins to be of a syrupy consistence; the residue mixed with three to four times its volume of alcohol, macerated for twenty-four hours at about 34°, allowed to become quite cool, and filtered from the foreign matters which have separated. The residue is washed with alcohol of 70 per cent.

III. The filtrate is freed from alcohol by distillation, the watery residue poured into a capacious flask, diluted (if necessary) with water, and filtered. Acid as it is, it is extracted at the common temperature, with frequent shaking, by freshly-rectified petroleum ether; and, after the fluids have again separated, the petroleum ether is removed, carrying with it certain impurities (colouring matter, &c.), which are in this way advantageously displaced. By this operation ethereal oils, carbolic acid, picric acid, &c., which have not been distilled, besides piperin, may also be separated. The shaking up with petroleum ether is repeated several times (as long as anything remains to be dissolved), and the products are evaporated on several watch-glasses.

RESIDUE OF PETROLEUM ETHER FROM THE ACID SOLUTION.

1. It is Crystalline.	2. It is Amorphous.	3. It is Volatile, with a powerful odour;
		ethereal oil, carbolic acid, &c.
A. It is yellowish, and with difficulty volatilised.	A. It is fixed.
α. The crystals are dissolved by concentrated sulphuric acid, with the production of a clear yellow colour, passing into brown and greenish-brown.	α. Concentrated sulphuric acid dissolves it immediately—violet, and later greenish-blue.
Piperin.	Constituents of the black hellebore.
β. The solution in sulphuric acid remains yellow; potassic cyanide and caustic potash colour it, on warming, blood-red.	β. It dissolves with a yellow colour, changing into fallow-brown.
Picric acid.	Constituents of aconite plant and products of the decomposition of Aconitine.
B. It Is Colourless, Liquefies easily, and Smells Strongly.	B. It Is White, Sharp-Tasting, and Reddens the Skin.
Camphor and similar matters.	Capsicin.

It may be expected that the substances mentioned under the heads 1, 2, and 3 will be, in general, fully obtained by degrees. This is not the case, however, as regards piperin and picric acid.

IV. The watery fluid is now similarly shaken up with benzene, and the benzene removed and evaporated. Should the evaporated residue show signs of an alkaloid (and especially of theine), the watery fluid is treated several times with a fresh mixture of benzene, till a little of the last-obtained benzene extraction leaves on evaporation no residue. The benzene extracts are now united, and washed by shaking with distilled water; again separated and filtered, the greater part of the benzene distilled from the filtrate, and the remainder of the fluid divided and evaporated on several watch-glasses.

The evaporated residue may contain theine, colchicine, cubebin, digitalin, cantharidin, colocynthin, elaterin, caryophylline, absinthin, cascarillin, populin, santonin, &c., and traces of veratrine, delphinine, physostigmine, and berberine.

A remnant of piperin and picric acid may remain from the previous treatment with petroleum ether.

THE BENZENE RESIDUE FROM THE ACID SOLUTION.

1. It is Crystalline.	2. It is Amorphous.
A. Well-formed, Colourless Crystals.	A. Colourless or Pale Yellow Residue.
α. Sulphuric acid dissolves the hair-like crystals without change of colour; evaporation with chlorine water, and subsequent treatment with ammonia, gives a murexide reaction.	α. Sulphuric acid dissolves it at first yellow; the solution becoming later red. Fröhde’s reagent does not colour it violet.
Theine.	Elaterin.
β. Sulphuric acid leaves the rhombic crystals uncoloured. The substance, taken up by oil, and applied to the skin, produces a blister.	β. Sulphuric acid dissolves red; Fröhde’s reagent violet-red;[333] tannic acid does not precipitate.
Cantharidin.	Populin.
γ. Sulphuric acid leaves the scaly crystals at first uncoloured, then slowly develops a reddening. It does not blister. Warm alcoholic potash-lye colours it a transitory red.	γ. Sulphuric acid dissolves it with a red colour; Fröhde’s reagent[334] a beautiful cherry-red; tannic acid precipitates a yellowish-white.
Santonin.	Colocynthin.
δ. Sulphuric acid colours the crystals almost black, whilst it takes itself a beautiful red colour.	δ. Sulphuric acid colours it gradually a beautiful red, whilst tannin does not precipitate.
Cubebin.	Constituents of the Pimento.
B. Crystals Pale to Clear Yellow.	B. Pure Yellow Residue.
α. Piperin.	α. Sulphuric acid dissolves it yellow; on the addition of nitric acid, this solution is green, quickly changing to blue and violet.
	Colchicine.
β. Picric Acid.	β. Sulphuric acid dissolves with separation of a violet powder; caustic potash colours it red; sulphide of ammonia violet, and, by heating, indigo-blue.
	Chrysammic acid.
γ. Caustic potash dissolves it purple.
Aloetin.
C. Mostly Undefined Colourless Crystals.	C. A Greenish Bitter Residue, which dissolves brown in concentrated sulphuric acid; in Fröhde’s reagent, likewise, at first brown, then at the edge green, changing into blue-violet, and lastly violet.
	Constituents of wormwood, with absynthin, besides quassiin, menyanthin, ericolin, daphnin, cnicin, and others.
α. Sulphuric acid dissolves it green-brown; bromine colours this solution red; dilution with water again green. The substance renders the heart-action of a frog slower.
Digitalin.
β. Sulphuric acid dissolves it orange, then brown, lastly red-violet. Nitric acid dissolves it yellow, and water separates as a jelly out of the latter solution. Sulphuric acid and bromine do not colour it red.
Gratiolin.
γ. Sulphuric acid dissolves it red-brown. Bromine produces in this solution red-violet stripes. It does not act on frogs.
Cascarillin.
D. Generally Undefined Yellow Crystallisation.—Sulphuric acid dissolves it olive-green. The alcoholic solution gives with potassic iodide a colourless and green crystalline precipitate.
Berberin.

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V. As a complete exhaustion of the watery solution is not yet attained by the benzene agency, another solvent is tried.

THE WATERY SOLUTION IS NOW EXTRACTED IN THE SAME WAY BY CHLOROFORM.

In chloroform the following substances are especially taken up:—Theobromine, narceine, papaverine, cinchonine, jervine, besides picrotoxin, syringin, digitalin, helleborin, convallamarin, saponin, senegin, smilacin. Lastly, portions of the bodies named in Process IV., which benzene failed to extract entirely, enter into solution, as well as traces of brucine, narcotine, physostigmine, veratrine, delphinine. The evaporation of the chloroform is conducted at the ordinary temperature in four or five watch-glasses.

THE CHLOROFORM RESIDUE FROM THE ACID SOLUTION.[335]

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1. The Residue is more or less markedly Crystalline.	2. The Residue is Amorphous.
A. It gives in the sulphuric acid solution evidence of an alkaloid by its action towards iodine and iodide of potassium.	A. In acetic acid solution it renders the action of the frog’s heart slower, or produces local anæsthesia.
	aa. It does not produce local anæsthesia.
α. Sulphuric acid dissolves it without the production of colour, and chlorine and ammonia give no murexide reaction.	α. Sulphuric acid dissolves it red-brown, bromine produces a beautiful purple colour, water changes it into green, hydrochloric acid dissolves it greenish-brown.
Cinchonine.	Digitalin.
β. Sulphuric acid dissolves it without colour, chlorine and ammonia give, as with theine, a murexide reaction.	β. Sulphuric acid dissolves it yellow, then brown-red; on addition of water this solution becomes violet. Hydrochloric acid, on warming, dissolves it red.
Theobromine.	Convallamarin.
	bb. It produces local anæsthesia.
	α. Sulphuric acid dissolves it brown. The solution becomes, by extracting with water, violet, and can even be diluted with two volumes of water without losing its colour.
	Saponin.
	β. Sulphuric acid dissolves it yellow. On diluting with water the same reaction occurs as in the previous case, but more feebly.
	Senegin.
γ. Sulphuric acid does not colour in the cold; on warming, the solution becomes a blue violet.	γ. Sulphuric acid dissolves brown, and the solution becomes red by the addition of a little water. The action is very weak.
Papaverine.	Smilacin.
	cc. Sulphuric acid dissolves it with the production of a dirty red, hydrochloric acid, in the cold, with that of a reddish-brown colour, and the last solution becomes brown on boiling.
	Constituents of the hellebore, particularly Jervine.
δ. Sulphuric acid dissolves it in the cold with the production of a blue colour.
Unknown impurities, many commercial samples of Papaverine.
ε. Sulphuric acid dissolves it at first grey-brown; the solution becomes in about twenty-four hours blood-red. Iodine water colours it blue.
Narceine.
B. It gives no Alkaloid Reaction.	B. Is inactive, and becomes blue by sulphuric acid; by Fröhde’s reagent[336] dark cherry-red. Hydrochloric acid dissolves it red. The solution becomes, by boiling, colourless.
	Syringin.
α. Sulphuric acid dissolves it with a beautiful yellow colour; mixed with nitre, then moistened with sulphuric acid, and lastly treated with concentrated soda-lye, it is coloured a brick-red.
Picrotoxin.
β. Sulphuric acid dissolves it with the production of a splendid red colour. The substance renders the heart-action of a frog slower.
Helleborin.

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VI. THE WATERY FLUID IS NOW AGAIN SHAKEN UP WITH PETROLEUM ETHER,

in order to take up the rest of the chloroform, and the watery fluid is saturated with ammonia. The watery solution of aconitine and emetine is liable to undergo, through free ammonia, a partial decomposition; but, on the other hand, it is quite possible to obtain, with very small mixtures of the substances, satisfactory reactions, even out of ammoniacal solutions.

VII. THE AMMONIACAL WATERY FLUID WITH PETROLEUM ETHER.

In the earlier stages Dragendorff advises the shaking up with petroleum ether at about 40°, and the removal of the ether as quickly as possible whilst warm. This is with the intention of separating by this fluid strychnine, brucine, emetine, quinine, veratrine, &c. Finding, however, that a full extraction by petroleum ether is either difficult or not practicable, he prefers, as we have seen, to conclude the operation by other agents, coming back again upon the ether for certain special cases. Such are the volatile alkaloids; and here he recommends treatment of the fluid by cold petroleum ether, taking care not to hasten the removal of the latter. Strychnine and other fixed alkaloids are then only taken up in small quantities, and the greater portion remains for the later treatment of the watery fluid by benzene.

A portion of the petroleum ether, supposed to contain in solution volatile alkaloids, is evaporated in two watch-glasses; to the one, strong hydrochloric acid is added, the other being evaporated without this agent. On the evaporation of the petroleum ether, it is seen whether the first portion is crystalline or amorphous, or whether the second leaves behind a strongly-smelling fluid mass, which denotes a volatile alkaloid. If the residue in both glasses is without odour and fixed, the absence of volatile acids and the presence of fixed alkaloids, strychnine, emetine, veratrine, &c., are indicated.

THE PETROLEUM ETHER RESIDUE FROM AMMONIACAL SOLUTION.

1. It is fixed and Crystalline.	2. It is fixed and Amorphous.	3. It is fixed and Odorous.
A. The crystals are volatilised with difficulty.		A. On adding to the watch-glass a little hydrochloric acid, crystals are left behind.
aa. Sulphuric acid dissolves it without colour.		aa. Its solution is not precipitated by platin chloride.
α. Potassic chromate colours this solution a transitory blue, then red.	α. The purest sulphuric acid dissolves it almost without colour; sulphuric acid containing nitric acid, red quickly becoming orange.	α. The crystals of the hydrochloric compound act on polarised light; and are mostly needle-shaped and columnar.
Strychnine.	Brucine.	Coniine and Methyl-Coniine.
β. Potassic chromate does not colour it blue; with chlorine water and ammonia it gives a green colour.	β. Sulphuric acid dissolves it yellow, becoming deep red.	β. The crystals are cubical or tetrahedral.
Quinine.	Veratrine.	Alkaloid from Capsicum.
	γ. Sulphuric acid dissolves it brown-green; Fröhde’s reagent red, changing into green.
	Emetine.
		bb. The solution of the hydrochlorate of the alkaloid is precipitated by platin chloride.
		Sarracinin.
γ. Sulphuric acid dissolves it yellow, and the solution becomes gradually a beautiful deep red.		B. The residue of the hydrochlorate of the alkaloid is amorphous, or, by further additions of HCl, becomes crystalline.
Sabadilline.
δ. The crystals are easily volatilised.
Coniine.
		aa. Its diluted aqueous solution is precipitated by platin chloride.
		α. The hydrochlorate salt, being quickly treated with Fröhde’s reagent, gives after about two minutes a violet solution which gradually fades.
		Lobeliin.
		β. The hydrochlorate smells like nicotine, and becomes by Fröhde’s reagent yellow, and after twenty-four hours pale red.
		Nicotine.
		γ. The hydrochlorate is without odour, the free base smells faintly like aniline.
		Sparteine.
		bb. The substance is not precipitated from a diluted solution by platin chloride.
		α. Its petroleum ether solution produces no turbidity with a solution of picric acid in petroleum ether; but it leaves behind, when mixed with the above, crystals mostly of three-sided plates.
		Trimethylamine.
		β. The petroleum ether solution gives, on evaporation, when treated similarly, moss-like crystals. The substance is made blue by chloride of lime, as well as by diluted sulphuric acid and bichromate of potash.
		Aniline.
		γ. The alkaloid does not smell like methylamine, and is not coloured by chloride of lime, sulphuric acid, or chromate of potash.
		Volatile alkaloid of the Pimento.

VIII. THE AMMONIACAL SOLUTION IS SHAKEN UP WITH BENZENE.

In most cases petroleum ether, benzene, and chloroform are more easily separated from acid watery fluids than from ammoniacal, benzene and chloroform causing here a difficulty which has perhaps deterred many from using this method. Dragendorff, however, maintains that he has never examined a fluid in which he could not obtain a complete separation of the benzene and water. If the upper benzene layer is fully gelatinous and emulsive, the under layer of water is to be removed with a pipette as far as possible, and the benzene with a few drops of absolute alcohol and filtration. As a rule, the water goes through first alone, and by the time the greater part has run through, the jelly in the filter, by dint of stirring, has become separated from the benzene, and, finally, the jelly shrinks up to a minimum, and the clear benzene filters off. Dragendorff filters mostly into a burette, from which ultimately the benzene and the water are separated.

The principal alkaloids which are dissolved in benzene are—strychnine, methyl and ethyl strychnine, brucine, emetine, quinine, cinchonine, atropine, hyoscyamine, physostigmine, aconitine, nepalin, the alkaloid of the Aconitum lycoctonum, aconellin, napellin, delphinine, veratrine, sabatrin, sabadilline, codeine, thebaine, and narcotine.

THE BENZENE RESIDUE DERIVED FROM THE AMMONIACAL SOLUTION.

1. It is for the most part Crystalline.	2. It is for the most part Amorphous.
a. Sulphuric acid dissolves it without colour, the solution being coloured neither on standing nor on the addition of nitric acid.	a. Pure sulphuric acid dissolves it either whitish-red or yellowish.
aa. It dilates the pupil of a cat.
α. Platin chloride does not precipitate the aqueous solution. The sulphuric acid solution gives, on warming, a peculiar smell.	α. The solution becomes by nitric acid immediately red, then quickly orange.
Atropine.	Brucine.
β. Platin chloride applied to the solution precipitates.	β. The solution becomes by little and little brownish-red. The substance is coloured red by chloride of lime solution, and it contracts the pupil.
Hyoscyamine.	Physostigmine.
bb. It does not dilate the pupil.
α. The sulphuric acid solution becomes blue by chromate of potash.
αα. The substance applied to a frog produces tetanus.
Strychnine.
ββ. It lowers the number of respirations in a frog.
Ethyl and Methyl Strychnine.
β. Sulphuric acid and bichromate of potash do not colour it blue.
αα. The sulphuric acid watery solution is fluorescent, and becomes green on the addition of chlorine water and ammonia.
Quinine and Cinchonine.
(The last is more difficult to dissolve in petroleum ether than quinine.)
ββ. The solution is not fluorescent.
Cinchonine.
b. Sulphuric acid dissolves it at first colourless; the solution takes on standing a rose or violet-blue; on addition of nitric acid, a blood-red or brown coloration.	b. Pure sulphuric acid dissolves it yellow, and the solution becomes later beautiful red (with delphinine, more quickly a darker cherry-red.)
α. A solution in diluted sulphuric acid becomes, on heating, gradually deep blood-red, and, when cooled, violet, with nitric acid. The aqueous solution is precipitated by ammonia.	α. The hydrochloric acid solution becomes red on heating.
Narcotine.
	αα. The substance acts on a frog, causing, in large doses, tetanus.
	Veratrine.
	ββ. It is almost without action on frogs.
	Sabatrin.
β. The solution in diluted sulphuric acid becomes, on heating, a beautiful blue. Excess of ammonia does not precipitate in a diluted watery solution.	β. The hydrochloric acid solution does not, on heating, become red.
Codeine.	Delphinine.
c. Sulphuric acid dissolves it with the production of a yellow colour.	c. Pure sulphuric acid dissolves it yellow, and the solution becomes later red-brown, and gradually violet-red.
α. The solution remains yellow on standing.	α. The substance even in small doses paralyses frogs, and dilates the pupil of a cat’s eye. Ether dissolves it with difficulty.
Acolyctin.	Nepalin.
β. It becomes beautifully red.	β. It is easily soluble in ether, its effects are not so marked, and it does not dilate the pupil.
Sabadilline.	Aconitine.
	γ. Its effects are still feeble; it does not dilate the pupil, and is with difficulty dissolved by ether.
	Napellin.
d. Sulphuric acid dissolves it with an immediate deep red-brown colour.	d. Sulphuric acid dissolves it with a dark green colour, and the solution becomes, even after a few seconds, a beautiful blood-red.
Thebaine.	Alkaloidal substances out of the Aconitum lycoctonum.
e. Sulphuric acid dissolves it immediately blue.	e. Sulphuric acid dissolves it brown-green, and Fröhde’s reagent red, becoming beautifully green.
Substances accompanying the Papaverins.	Emetine.

IX. SHAKING OF THE AMMONIACAL WATERY SOLUTION WITH CHLOROFORM.

This extracts the remainder of the cinchonine and papaverine, narceine, and a small portion of morphine, as well as an alkaloid from the celandine.

The Residue from the Chloroform.

aa. The solution, on warming, is only slightly coloured.

α. But, after it is again cooled, it strikes with nitric acid a violet-blue; chloride of iron mixed with the substance gives a blue colour; Fröhde’s reagent also dissolves it violet.

Morphine.

β. It is not coloured by nitric acid; it is also indifferent to chloride of iron.

Cinchonine.

bb. The solution becomes by warming violet-blue.

Papaverine.

γ. Sulphuric acid dissolves it greenish-brown, and the solution becomes, on standing, blood-red.

Narceine.

δ. Sulphuric acid dissolves it a violet-blue.

Alkaloidal constituent of the Celandine.

X. SHAKING UP OF THE WATERY FLUID WITH AMYL ALCOHOL.

From this process, besides morphine and solanine, as well as salicin, the remnants of the convallamarin, saponin, senegin, and narceine are also to be expected.

The Amyl Alcohol Residue.

a. Sulphuric acid dissolves it without colour in the cold.

Morphine (see above).

b. Sulphuric acid dissolves it with the production of a clear yellow-red and the solution becomes brownish. Iodine water colours it a deep brown. The alcoholic solution gelatinises.

Solanine.

c. Sulphuric acid dissolves it green-brown, becoming red.

Narceine (see above).

d. Sulphuric acid dissolves it yellow, then brown-red, becoming violet on dilution with water. Hydrochloric acid dissolves it, and it becomes red on warming. It stops the heart-action in the systole.

Convallamarin.

e. Hydrochloric acid dissolves it for the most part without colour.

Saponin.

f. As the foregoing, but acting more feebly.

Senegin.

g. Sulphuric acid dissolves it immediately a pure red. On warming with sulphuric acid and bichromate of potash, a smell of salicylic acid is developed.

Salicin.

XI. DRYING THE WATERY FLUID WITH THE ADDITION OF POWDERED GLASS, AND EXTRACTION OF THE FINELY-DIVIDED RESIDUE BY CHLOROFORM.

The residue of the first chloroform extract lessens the number of respirations of a frog; the residue of the second and third chloroform extract becomes, by sulphuric acid and bichromate of potash, blue, passing into a permanent red.

Another portion of this residue becomes red on warming with diluted sulphuric acid.

Curarine.

Shorter Process for Separating some of the Alkaloids.

§ 310. A shorter process, recommended conditionally by Dragendorff, for brucine, strychnine, quinine, cinchonine, and emetine, is as follows:—

The substance, if necessary, is finely divided, and treated with sulphuric acid (dilute) until it has a marked acid reaction. To every 100 c.c. of the pulp (which has been diluted with distilled water to admit of its being filtered later), at least 5 to 10 c.c. of diluted sulphuric acid (1 : 5) are added. It is digested at 50° for a few hours, filtered, and the residue treated again with 100 c.c. of water at 50°. This extract is, after a few hours, again filtered; both the filtrates are mixed and evaporated in the water-bath to almost the consistency of a thin syrup. The fluid, however, must not be concentrated too much, or fully evaporated to dryness. The residue is now placed in a flask, and treated with three to four times its volume of alcohol of 90 to 95 per cent.; the mixture is macerated for twenty-four hours, and then filtered. The filtrate is distilled alcohol-free, or nearly so, but a small amount of alcohol remaining is not objectionable. The watery fluid is diluted to about 50 c.c., and treated with pure benzene; the mixture is shaken, and after a little time the benzene removed—an operation which is repeated. After the removal the second time of the benzene, the watery fluid is made alkaline with ammonia, warmed to 40° or 50°, and the free alkaloid extracted by twice shaking it up with two different applications of benzene. On evaporation of the latter, if the alkaloid is not left pure, it can be dissolved in acid, precipitated by ammonia, and again extracted by benzene.