b. METHOD RECOMMENDED BY E. PROLLIUS.

Boil twice with spirit of wine, mixed with some tartaric acid, evaporate at a gentle heat, filter the residuary acid aqueous solution through a moistened filter, add ammonia in slight excess, then from 20 to 25 grains (about 14 grm.) of chloroform, shake, free the deposited chloroform thoroughly from the ley, by decanting and shaking with water, mix the chloroform so purified with 3 parts of spirit of wine, and let the fluid evaporate. If there is any notable quantity of strychnia present, it is obtained in crystals.

5. METHOD OF EFFECTING THE DETECTION OF STRYCHNIA IN BEer, BY Graham AND A. W. Hofman.t

This method, which is based on the known fact that a solution of a salt of strychnia, when mixed and shaken with animal charcoal, yields its strychnia to the charcoal, will undoubtedly be found applicable also for the detection of other alkaloids. The process is conducted as follows:

Shake 2 ounces of animal charcoal in half-a-gallon of the aqueous neutral or feebly acid fluid under examination; let the mixture stand for from 12 to 24 hours, with occasional shaking, filter, wash the charcoal twice with water, then boil for half-an-hour with 8 ounces of spirit of wine of 80-90 per cent., avoiding loss of alcohol by evaporation. Filter the spirit of wine hot from the charcoal, and distil the filtrate; add a few drops of solution of potassa to the residual watery fluid, shake with ether, let the mixture stand at rest, then decant the supernatant ether. The ethereal fluid leaves, upon spontaneous evaporation, the strychnia in a stateof sufficient purity to admit of its further examination by reagents (see § 240).

MACADAM employed the same method in his numerous experiments to detect strychnia in the bodies of dead animals. He treated the comminuted matters with a dilute aqueous solution of oxalic acid in the cold, filtered through muslin, washed with water, heated to boiling, filtered still warm, from the coagulated albuminous matters, shook with charcoal, and proceeded in the manner just described. According to his statements, the residue left by the evaporation of the alcoholic solution was generally at once fit to be tested for strychnia. Where it was not so, he treated the residue again with solution of oxalic acid, and repeated the process with

animal charcoal.

6. SEPARATION BY DIALYSIS.

The dialytic method devised by GRAHAM, and described in § 227, *Chem. Centrabl., 1857, 231.

+ Chem. Soc. Quart. Journ., v. 173.

Pharm. Journ. Trans., xvi. 120, 160.

may also be advantageously employed to effect the separation of alkaloids from the contents of the stomach, intestines, &c. Acidify with hydrochloric acid, and place the matter in the dialyser. The alkaloids, being crystalline bodies, penetrate the membrane, and are found, for the greater part, after 24 hours, in the outer fluid; from this they may, then, according to circumstances, either be thrown down at once, after concentration by evaporation; or they may be purified by one of the above described methods.

II.

GENERAL PLAN OF THE ORDER AND SUCCESSION IN WHICH SUBSTANCES SHOULD BE ANALYZED FOR PRACTICE.

§ 248.

It is not a matter of indifference whether the student, in analyz ing for the sake of practice, follows no rule or order whatever in the selection of the substances which he intends to analyze, or whether, on the contrary, his investigations and experiments proceed systematically. Many ways, indeed, may lead to the desired end, but one of them will invariably prove the shortest. I will, therefore, here point out a course which experience has shown to lead safely and speedily to the attainment of the object in view. Let the student take 100 compounds, systematically arranged (see below), and let him analyze these compounds successively in the order in which they are placed. A careful and diligent examination of these will be amply sufficient to impart to him the necessary degree of skill in practical analysis. When analyzing for the sake of practice only, the student must above all things possess the means of verifying the results obtained by his experiments. The compounds to be examined ought, therefore, to be mixed for him by a friend who knows their exact composition.

A. From 1 to 20.

AQUEOUS SOLUTIONS OF SIMPLE SALTS: e. g., sulphate of soda, nitrate of lime, chloride of copper, &c. These investigations will serve to teach the student the method of analyzing substances soluble in water which contain but one base. In these investigations it is only intended to ascertain which base is present in the fluid under examination; but neither the detection of the acid, mor the proof of the absence of all other bases besides the one detected, is required.

B. From 21 to 50.

SALTS, ETC., CONTAINING ONE BASE AND ONE ACID, OR ONE METAL AND ONE METALLOID (in form of powder: e. g., carbonate of baryta, borate of soda, phosphate of lime, arsenious acid, chloride of sodium, bitartrate of potassa, acetate of copper, sulphate of baryta, chloride of lead, &c. These investigations will serve to teach the student how to make a preliminary examination of a solid substance, by heating in a tube or before the blowpipe; how to convert it into a proper form for analysis, i. e., how to dissolve or decompose it; how to detect one metallic oxide, even in substances insoluble in water; and how to demonstrate the presence of one acid. The detection of both the base and the acid is required, but it is not necessary to prove that no other bodies are present.

C. From 51 to 65.

AQUEOUS OR ACID SOLUTIONS OF SEVERAL BASES. These investigations will serve to teach the student the method of separating and distinguishing several metallic oxides from each other. The proof is required that no other bases are present besides those detected. No regard is paid to the acids.

D. From C6 to 80.

DRY MIXTURES OF EVERY DESCRIPTION. A portion of the salts hould be organic, another inorganic; a portion of the compounds soluble in water or hydrochloric acid; another insoluble; e. g., mixtures of chloride of sodium, carbonate of lime, and oxide of copper; of phosphate of magnesia and ammonia, and arsenious acid; of tartrate of lime, oxalate of lime, and sulphate of baryta ;of phosphate of soda, nitrate of ammonia, and acetate of potassa, &c. These investigations will serve to teach the student how to treat mixtures of different substances with solvents;. how to detect several acids in presence of each other; how to detect the bases in presence of phosphates of the alkaline earths; and they will serve as a general introduction to scientific and practical analysis. All the component parts must be detected, and the nature of the substance ascertained.

E. From 81 to 100.

NATIVE COMPOUNDS, ARTICLES OF COMMERCE, &c. Mineral and other waters, minerals of every description, soils, potash, soda. alloys, colors, &c.

III.

ARRANGEMENT OF THE RESULTS OF THE ANALYSIS PERFORMED

FOR PRACTICE.
§ 249.

The manner in which the results of analytical investigations ought to be arranged is not a matter of indifference. The following examples will serve to illustrate the method which I have found the most suitable in this respect.

PLAN OF ARRANGING THE RESULTS OF EXPERIMENTS, Nos. 1—20. Colorless fluid of neutral reaction.

PLAN OF ARRANGING THE RESULTS OF EXPERIMENTS, Nos. 21--50. White powder, fusing in the water of crystallization upon application of heat, then remaining unaltered-soluble in water-reac tion neutral.

The detected base being Mg O, and the analyzed substance being soluble in water, the acid can only be Cl, I, Br, SO, NO, A, &c. The preliminary examination has proved the absence of the organic acids, and of nitric acid.

Ba Cl produces a white precipitate which H Cl fails to dissolve; consequently SULPHURIC ACID.