Sixty-four analyses of commercial samples of cocoa and chocolate have been made in the U.S. Agricultural Laboratory, and the general results may be classified as follows:

A. Samples of cocoa or chocolate in commerce without any admixture, but most of them evidently showing treatment by steam or alkalies.

C. Cocoas and chocolates mixed with wheat, flour, and sugar.

Maximum,

Minimum,
Mean,

2:46 28.72 1.85 3.29 2.70 1.58 60.0 0.97 1.25 0:46 510 1.55 1.86 1.28 56.7

0.85 16.92 0.81
1.71 20.79 1.14

D. Cocoas and chocolates mixed with arrowroot and sugar.

Maximum,

Minimum,
Mean,

2.5 28.79 1.20 3.15
0.6 11.13 2.62 1.40
1.4 22.80 1.85 2.30

4.60 1.63 51.00

2.25 0.83 25-00 3:08 1.37 36:4

R. Bensemann lays stress on the relations between the fat, starch, and matters insoluble in water. Designating the starch by S, the fat by F, the insoluble matters in water by U, the starch divided by the difference between the fat and matters insoluble in water gives what Bensemann calls "the starch coefficient," and is an aid to estimating the admixture of cocoa with flour or starch. He also gives other coefficients. This method and its results can be gathered from his analysis as follows:

TABLE XXXc.-NUMERICAL RELATIONS BETWEEN THE VARIOUS CON

STITUENTS OF THE COCOAS IN THE PRECEDING TABLE AS CALCULATED
BY BENSEMANN.

starch; F = fat; U total organic matter insoluble in water.

§ 224. Stutzer classifies the nitrogenous constituents of cocoa as follows:

:

1. Non-proteids, substances soluble in neutral water solution in presence of copper hydrate (theobromin, ammonia, and amido compounds).

2. Digestible albumen.

3. Insoluble and indigestible nitrogenous substance. In three samples he found the mean numbers in per cent. of total nitrogen to be-soluble non-proteid nitrogen 29.4 per cent., albumen 32.2 per cent., and not digestible 38.4 per cent. Mr. Wigner's examination of the nitrogenous constituents of cocoa, based on 84 commercial samples, are as follows:

§ 225. Adulterations of Cocoa.-The list of adulterations usually given is as follows:-Sugar, starches, Venetian red, brick-dust, and peroxide of iron. Some of these sophistications, such as the starches, may be detected by a preliminary microscopical examination, which in no instance should be neglected. The ordinary chemical examination consists in the extraction of the fat as before described, the estimation of the percentage of ash in the ordinary way, its division into soluble and insoluble, and its content of phosphoric acid. By a simple estimation of the fat and the chief constituents of the ash, supplemented by the use of the microscope, all known adulterations can be detected. The amount of phosphoric acid in the ash of soluble cocoas has been taken as a basis of calculation of the amount of cocoa, and in the absence of foreign seeds, or other phosphate-producing

substance, the calculation will be a fair approximation to the truth. The ash itself and the amount of phosphoric acid will, of course, be very notably diminished in the case of the soluble cocoas, and the percentage of the phosphoric acid will in such instances be a fair guide to the amount of foreign admixture. For example, suppose a soluble cocoa to yield an ash of 1.5 per cent, 6 of which is due to phosphoric acid, taking as a basis of calculation 9 per cent.* of phosphoric acid in cocoa nibs :

:

That is, the mixture contains about 66.6 per cent. of cocoa. The amount of starch in cocoa may be determined in the ordinary way, as described at p. 165 et seq., but the process is somewhat tedious, and may be dispensed with, since the extract in cold water is always a guide to the adulteration by starchy substances. Cocoa nibs treated in this way give to water about 6.76 per cent. of organic matter and 216 of ash. The determination of theobromin and of cocoa red is also of use.

§ 226. Adulterations of Chocolate.-Oil of almonds, cocoa-oil, beef and mutton fat, starches, cinnabar, chalk, and various other substances are usually enumerated; a few of these are, however, apocryphal.

The analysis of chocolate is conducted on exactly the same principles as that of soluble cocoa. If it is desired to separate the different constituents, the method recommended by A. Porrier may be used-Extract the fat with ether, and the sugar with alcohol of 20°, and dissolve the starch out by boiling water. The liquid holding the starch is then decolorised by animal charcoal, and the starch precipitated by alcohol of 50 per cent., dried, and weighed. But as regards adulteration, the procedure recommended in the case of cocoa will be found quite efficient, and less cumbersome and tedious.

BIBLIOGRAPHY.

BARBET.-Procédé pour reconnaître la quantité de fécule contenue dans les chocolats. Journ. Chim. Méd., 4e série, 1857, t. iii., p. 121. BENSEMANN. Various papers on Cocoa and Chocolate. Ber. d. chem. Ges., xvi., 856; Rep. f. anal. Chem., iv., 213; Zeit. f. anal. Chem., xxiv., 628.

*The lowest percentage given by Mr. Heisch, and but little different from Mr. Wanklyn's.