In a solution of terchloride of gold, conicine produces a light-yellow precipitate.

In a solution of bichloride of platinum, it produces a similar precipitate; absence of ammoniacal salts is necessary.

In a great many other metallic salts it causes precipitates, resembling those produced by ammonia.

On adding a solution of iodine (prepared from iodine, water, and a particle of iodide of potassium) to a watery solution of conicine, a kermes-brown precipitate is thrown down. With very little solution of iodine only, a turbidness of sulphur-yellow color is produced, and the liquid becomes, after a short time, colorless.

A solution of tannine causes a whitish turbidness and precipitate.

On gradually adding chlorine-water to a watery solution of conicine, the liquid becomes white and turbid.

[On passing a current of chlorine-gas through conicine, thick white fumes are formed at first; after a while, the temperature commences to rise, and the liquid assumes a blood-red color; on continuing the operation, the liquid becomes again colorless, thickens, and is finally converted into a white, crystalline mass.]

In solutions of the salts of conicine terchloride of gold produces a light yellow, and a solution of iodine a kermes-brown precipitate.

From nicotine the conicine is best distinguished by its odor and by its inferior solubility in water; also by the color of the chloride of gold precipitate which is of a lighter yellow in the case of conicine,

and by the reaction with chlorine-water, which does not produce a whitish turbidness with nicotine.

§ 106. Morphine.-It occurs in small, colorless prisms, or as a crystalline powder. It is little soluble in water, more so in alcohol, especially on boiling. Ether dissolves only a very small quantity. A solution of caustic soda dissolves a considerable portion. With acids it forms salts, which are soluble in alcohol. The sulphate, acetate, and chloride of morphine are soluble in water, the latter not to a great extent. The chloride crystallizes easily in long delicate prisms. An excess of acid increases their solubility; even those salts which are insoluble in pure water dissolve in presence of an excess of acid. The most important reactions of morphine are as follows:

On adding morphine to concentrated nitric acid, the latter assumes a blood-red color, which gradually passes into yellow.

On adding morphine, or a salt of morphine, to a solution of iodic acid, iodine is set free; the iodine either falls to the bottom or remains dissolved in the. liquid, imparting to it a brown color. The liberated iodine is recognizable by the odor. If some starch was previously added to the solution of iodic acid, this becomes, of course, blue, on addition of the morphine.

[It must be borne in mind that albuminous liquids, lithic acid, and many other organic compounds, act in this manner on a solution of iodic acid. The test is, therefore, not conclusive.]

A neutral solution of sesquichloride of iron produces in a neutral, or nearly neutral, solution of a

salt of morphine, a blue precipitate. The blue color soon passes into a dirty green and brown.

[The color is destroyed by alcohol, and by acetic ether; also by heat. In presence of meconic acid the color is red, instead of blue.]

Bichloride of platinum gives a granular orangeyellow precipitate.

From a solution of terchloride of gold the metal is gradually reduced.

Some morphine is placed in a small porcelain dish, a few drops of concentrated sulphuric acid are added, and heat is applied until solution has taken place. On diluting with a little water, and placing a particle of chromate of potassa into the liquid, the latter assumes an intensive mahogany-brown color.

§ 107. Narcotine.-It crystallizes in pretty large, colorless, lustrous prisms, less frequently in, scales. It is insoluble in water. It requires 100, parts of cold, and 20 parts of boiling alcohol for its solution. Ether dissolves on boiling th of its own weight of narcotine; from an ethereal solution it is deposited, on evaporation, in comparatively large prismatic crystals. With acids it forms salts, all of which possess an acid reaction, and an exceedingly bitter

taste.

It is distinguished from morphine, 1st, by its solubility in ether; 2d, by its insolubility in water containing acetic acid (by either of these two solvents it may be separated from morphine); 3d, by not producing a blue color with sesquisalts of iron, and, 4th. by its reaction with sulphuric acid, containing a trace of nitric acid. This test, which is the most

characteristic for narcotine, is executed in the following manner:

Some nicotine is placed in concentrated sulphuric acid, to which a very slight quantity of nitric acid has previously been added, and heat applied; the liquid assumes a blood-red color [which disappears again on addition of more nitric acid.]

§ 108. Strychnine.-Strychnine occurs either in white, lustrous prisms, or octahedrons, or as a white powder. It is very little soluble in water and ether, more soluble in alcohol, especially on boiling. With acids it forms salts which are soluble in alcohol; the sulphate, nitrate, and chloride are also dissolved by water. In presence of free acid, even those which are only slightly soluble in pure water, become soluble. Nitrate of strychnine crystallizes readily in long, slender prisms.

Its most important reactions are as follows:

Strychnine and its salts possess an exceedingly bitter taste. [The taste is, according to Christison's recent trials, the best "guide test." He has found no indication by the color-test beyond the 15,000th of a grain of pure strychnine in distilled water, while he perceived the sense of bitterness in distilled water when the strychnine formed only the 40,000th of a grain.-Taylor, "On Poisoning by Strychnine," p. 113.]

A solution of tannine, with the solution of a salt of strychnine gives a white precipitate.

Sulphocyanide of potassium gives a white, crystalline precipitate.

Terchloride of gold gives a reddish-yellow precipi

tate.

Bichloride of platinum gives a yellow, granular precipitate.

Chlorine-water gives a white precipitate, which is soluble in ammonia. [If a current of chlorine-gas is passed through a very dilute solution of strychnine, every gas-bubble, as it rises through the liquid, becomes surrounded with a white coating; on arriving at the surface, it breaks and sinks to the bottom in the shape of a white crystalline powder, which is insoluble in water, even on boiling, but soluble in alcohol and ether. If chlorine-gas is passed through a solution of nitrate of strychnine, a white precipitate is produced; when separated from the liquid by filtration, and treated with sulphuric acid, it assumes a fine rose-color.-Schlienkamp.]

On adding strychnine to nitric acid of moderate strength, the liquid assumes a yellow color. Strychnine containing brucine produces, under the same circumstances, a red color, similar to that produced by morphine. [With concentrated nitric acid, the color is in the first moment rose-red, then brown-yellow, and afterwards light yellow.]

On dissolving strychnine in a few drops of concentrated sulphuric acid, and placing in the liquid a small crystal of bichromate of potassa, the acid assumes, round the crystal, a beautiful blue or violet color. Instead of this salt, the deutoxide of lead, or, according to Davy, ferrocyanide of potassium may be employed. In my opinion, the bichromate of potassa deserves, after all, the preference. If the