The addition of bicarbonate of soda to an acid solution of strychnia causes no precipitation, and it is only after the lapse of twenty-four hours, or even a longer period, that strychnia crystallizes from the fluid in distinct prisms, in proportion as the free carbonic acid escapes. If a concentrated solution of strychnia, supersaturated with bicarbonate of soda, is boiled for some time, a precipitate forms immediately; from dilute solutions this precipitate separates only after concentration.

6. Sulphocyanide of potassium produces in concentrated solution of salts of strychnia immediately, and in dilute solutions after the lapse of some time, a white crystalline precipitate, which appears under the microscope as an aggregate of flat needles, truncated or pointed at an acute angle, and is but little soluble in an excess of the precipitant.

7. On putting a drop of concentrated sulphuric acid in a watch-glass, and adding to it some strychnia or a little of a salt of strychnia, solution ensues without any particular reaction; but if a drop of solution of chromate of potassa is now added to the fluid, the latter instantly acquires a deep blue color, which speedily changes to red (Otto). If the strychnia is rubbed together with binoxide of lead and concentrated sulphuric acid containing 1 per cent. of nitric acid, the mass acquires first a blue, then a violet color, which changes to red, and, finally, to greenish-yellow (E. Marchand). The former reaction (Otto's) loses in distinctness, or even altogether fails to manifest itself, if the substance contains admixtures of some other organic compounds, e. g., quina, sugar (Brieger). But by the second method (Marchand's) strychnia may be clearly detected even when mixed with much sugar. Ferricyanide of potassium also will produce the same reaction (W. Davy); with this oxidizing agent the change from violet to red and yellow takes place more slowly.

8. Chloride of mercury produces in solutions of salts of strychnia a white precipitate, which changes after some time to crystalline needles aggregated into stars, and distinctly visible through a lens. Upon heating the fluid these crystals redissolve, and upon subsequent cooling of the solution the double compound recrystallizes in distinct needles. 9. Strong chlorine water produces in solution of salts of strychnia a white precipitate, which dissolves in ammonia to a colorless fluid.

10. Concentrated nitric acid dissolves strychnia and its salts to a colorless fluid, which becomes yellow upon the application of heat.

1. Crystallized brucia (Br+7 aq.) appears either in the form of transparent, straight rhombic prisms, or in that of crystalline needles aggregated into stars, or as a white powder composed of minute crystalline scales. Brucia is difficultly soluble in cold, but somewhat more readily in hot water. Both absolute and dilute alcohol dissolve it freely, but it is insoluble in ether. Its taste is intensely bitter. When heated, it fuses with loss of its water of crystallization.

2. Brucia neutralizes acids completely. The salts of brucia are readily soluble in water, and of an intensely bitter taste. Most of them are crystallizable.

3. Potassa and carbonate of soda throw down from solutions of salts

of brucia a white precipitate of brucia, which is insoluble in an excess of the precipitant. Viewed under the microscope, immediately after precipitation, it appears to consist of very minute grains; but, upon further inspection, these grains are seen-with absorption of water-to suddenly form into needles, which latter subsequently arrange themselves into concentric groups. These successive changes of the precipitate may be traced distinctly even with the naked eye.

4. Ammonia produces a whitish precipitate in solutions of salts of brucia, which appears at first like a number of minute drops of oil, but changes subsequently-with absorption of water-to small needles. The precipitate redissolves, immediately after separation, very readily in an excess of the precipitant, but after a very short time-or, in dilute solutions, after a more considerable lapse of time-the brucia, combined with crystallization water, crystallizes from the ammoniacal fluid in small concentrically grouped needles, which addition of ammonia fails to redissolve.

5. Bicarbonate of soda produces in neutral solutions of salts of brucia a precipitate of brucia, combined with crystallization water; this precipitate separates after the lapse of a short time, in form of concentrically aggregated needles of silky lustre, which are insoluble in an excess of the precipitant, but dissolve in free carbonic acid (compare strychnia). Bicarbonate of soda fails to precipitate acid solutions of salts of brucia ; and it is only after the lapse of a considerable time that the alkaloid separates from the fluid in regular and comparatively large crystals, in proportion as the carbonic acid escapes.

6. Concentrated nitric acid dissolves brucia and its salts to intensely red fluids, which subsequently acquire a yellowish-red tint, and turn completely yellow upon application of heat. Upon addition of protochloride of tin or sulphide of ammonium to the fluid heated to this point, no matter whether concentrated or after dilution with water, the faint yellow color changes to a most intense violet.

7. Addition of chlorine water to the solution of a salt of brucia imparts to the fluid a fine bright red tint; if ammonia is then added, the red color changes to yellowish-brown.

8. Concentrated sulphuric acid dissolves brucia to a faint rose-colored fluid.

9. Sulphocyanide of potassium produces in concentrated solutions of salts of brucia immediately, and in dilute solutions after some time, a granular crystalline precipitate, which, when viewed under the microscope, appears composed of variously aggregated polyhedral crystalline grains. Friction applied to the sides of the vessel promotes the separation of the precipitate.

10. Chloride of mercury also produces a white granular precipitate, which, when viewed under the microscope, appears composed of small round crystalline grains.

+

c. VERATRIA, or VERATRINE (C,, H22 NO) Ve.

§ 237.

1. Veratria appears generally as a pure white, yellowish or greenishwhite powder, of acrid and burning, but not bitter taste; it is exceedingly poisonous. Veratria acts with great energy upon the mem

branes of the nose; even the most minute quantity of the powder excites the most violent sneezing. It is insoluble in water; in alcohol it dissolves readily, but more sparingly in ether. At a gentle heat it fuses like wax, and solidifies upon cooling to a transparent yellow

mass.

2. Veratria neutralizes acids completely. Some salts of veratria are crystallizable, others dry up to a gummy mass. They are soluble in water, and of acrid and burning taste.

3. Potassia, ammonia, and the simple carbonates of the alkalies produce in solutions of salts of veratria a flocculent, white precipitate, which, viewed under the microscope, immediately after precipitation, does not appear crystalline. After the lapse of a few minutes, however, it alters its appearance, and small scattered clusters of short prismatic crystals are observed, instead of the original coagulated flakes. The precipitate does not redissolve in an excess of potassa, and of carbonate of potassa. It is slightly soluble in ammonia, in the cold, but the dissolved portion separates again upon application of heat.

4. With bicarbonate of soda and bicarbonate of potassa the salts of veratria comport themselves like those of strychnia and brucia. However, upon boiling, the veratria separates readily, even from dilute solutions.

5. If veratria is acted upon with concentrated nitric acid, it agglutinates into small resinous lumps, which afterwards dissolve slowly in the acid. The solution presents a faint reddish-yellow color.

6. If veratria is treated with concentrated sulphuric acid, it also agglutinates at first into small resinous lumps; but these dissolve with great readiness to a pale yellow fluid, the color of which gradually increases in depth and intensity, and changes afterwards to a reddishyellow, then to an intense blood-red, subsequently to crimson, and finally to violet.

7. Sulphocyanide of potassium produces only in concentrated solutions of salts of veratria flocculent-gelatinous precipitates.

8. Addition of chlorine-water to the solution of a salt of veratria imparts to the fluid a yellowish tint, which, upon addition of ammonia, changes to a faint brownish color. In concentrated solutions chlorine produces a white precipitate.

Recapitulations and Remarks.

§ 238.

The alkaloids of the third group also are precipitated by many other reagents besides those above-mentioned, as, for instance, by tincture of galls, bichloride of platinum, &c. But as these reactions are common to all, they are of little importance in an analytical point of view.

Strychnia may be separated from brucia and veratria by means of absolute alcohol, since it is insoluble in that menstruum, whilst the two latter alkaloids readily dissolve in it. The identity of strychnia is best established by the reaction with sulphuric acid and chromate of potassa, or with binoxide of lead or ferricyanide of potassium; also by the form of its crystals-when thrown down by alkalies-viewed under the microscope; and lastly, by the form of the precipitate which sulphocyanide of potassium and chloride of mercury produce in solutions of its salts.

Brucia and veratria are not readily separated from one another, but may be detected in presence of each other. The identity of brucia is best established by the reactions with nitric acid and protochloride of tin or sulphide of ammonium, or by the form of the precipitate which ammonia produces in solutions of salts of brucia. Veratria is sufficiently distinguished from brucia and the other alkaloids which we have treated of, by its characteristic deportment at a gentle heat, and also by the form of the precipitate which alkalies produce in solutions of its salts. To distinguish veratria in presence of brucia, the reaction with concentrated sulphuric acid is employed.

To these alkaloids I will add salicine, although this substance does not properly belong to the same class of chemical compounds.

1. Salicine appears either in the form of white crystalline needles and scales of silky lustre, or, when the crystals are very small, as a powder of silky lustre. It has a bitter taste, is readily soluble in water and in alcohol, but insoluble in ether.

2. No reagent precipitates salicine as such.

3. If salicine is treated with concentrated sulphuric acid, it agglutinates into a resinous lump, and acquires an intensely blood-red color, without dissolving in the acid; the color of the sulphuric acid is at first unaltered.

4. If an aqueous solution of salicine is mixed with hydrochloric acid or dilute sulphuric acid, and the mixture boiled for a short time, the fluid suddenly becomes turbid, and deposits a finely granular crystalline precipitate (saliretine).

SYSTEMATIC COURSE FOR THE DETECTION OF THE ALKALOIDS TREATED OF IN THE PRECEDING PARAGRAPHS, AND OF SALICINE.

§ 240.

The analytical course which I am now about to describe is based upon the supposition that the analyst has to examine a concentrated aqueous solution-effected by the agency of an acid-of one or several of the nonvolatile alkaloids, which solution is free from any admixture of substances that might tend to obscure or modify the reactions. For the modifications which the presence of coloring or extractive matters, &c., requires, I refer to § 243.

I. DETECTION OF THE ALKALOIDS, AND OF SALICINE, IN SOLUTIONS SUPPOSED TO CONTAIN ONLY ONE OF THESE SUBSTANCES.

§ 241.

1. Add dilute solution of potassa or soda drop by drop to a portion of the aqueous solution, until the fluid acquires a scarcely perceptible alkaline reaction; stir, and let the fluid stand for some time.

a. NO PRECIPITATE IS FORMED; this proves the total absence of the alkaloids, and indicates the presence of SALICINE. To set all doubt at

rest, test the original substance with concentrated sulphuric acid, and also with hydrochloric acid. Compare § 239.

b. A PRECIPITATE IS FORMED. Add solution of potassa or soda, drop by drop, until the fluid manifests a strongly alkaline reaction.

a. The precipitate redissolves: MORPHIA. To arrive at a positive conclusion on this point, test another portion of the solution with iodic acid (§ 230, 8), and a portion of the original substance with nitric acid (§ 230, 6).

B. The precipitate remains undissolved: Presence of an alkaloid of the second or third group. Pass on to 2.

2. Add to a second portion of the original solution two or three drops of dilute sulphuric acid, and then a saturated solution of bicarbonate of soda until the acid reaction is just neutralized; vigorously rub the inside of the vessel, and allow the mixture to stand for half an hour.

a. No PRECIPITATE IS FORMED: Absence of narcotina and cinchonia. Pass on to 3.

b. A PRECIPITATE IS FORMED: Narcotina, cinchonia, and perhaps also quina, as the precipitation of the latter substance by bicarbonate of soda depends entirely upon the degree of dilution of the fluid. Add to a portion of the original solution ammonia in excess, then a sufficient quantity of ether, and shake the mixture.

a. The precipitate which forms at first upon the addition of the ammonia redissolves in the ether, and the clear fluid presents two distinct layers: narcotina or quina. To distinguish between the two, test a fresh portion of the original solution with chlorine water and ammonia. If the solution turns green, QUINA, if yellowish-red, NARCOTINA is present.

B. The precipitate which forms upon the addition of ammonia does not redissolve in the ether: CINCHONIA. The deportment of cinchonia at a high temperature may serve as a conclusive test (§ 233, 3). 3. Put a portion of the original substance, or of the residue remaining upon the evaporation of the solution, in a watch-glass, and treat with concentrated sulphuric acid.

a. A rose-colored solution is obtained, which becomes intensely red upon addition of nitric acid: BRUCIA. The reaction with nitric acid and protochloride of tin is resorted to as a conclusive test (§ 236, 6).

b. A yellow solution is obtained, the color of which gradually changes to yellowish-red, then to blood-red, and turns finally crimson: VERATRIA. c. A colorless fluid is obtained, which remains colorless after standing for some time.

Add to the fluid a drop of chromate of potassa; if this imparts to it a deep blue color, STRYCHNIA is present; if it leaves the fluid unaltered, QUINA is present. The reaction with chlorine water and ammonia is resorted to as a conclusive test.

II. DETECTION OF THE ALKALOIDS, AND OF SALICINE, IN SOLUTIONS SUPPOSED TO CONTAIN SEVERAL OR ALL OF THESE SUBSTANCES.

§ 242.

1. Add to a portion of the aqueous solution dilute solution of potassa or soda, drop by drop, until the fluid acquires a scarcely perceptible alkaline reaction; stir, and let the fluid stand for some time.

a. No PRECIPITATE IS FORMED; this proves the total absence of the