The most thorough and comprehensive analysis of the properties of cocoa is given by J. Alfred Wanklyn, in "A Practical Treatise on the Analysis of Tea, Coffee, Cocoa, Chocolate, etc.," published in London, in 1874. The following table gives the results obtained by the leading authorities: -

Lampedius.

Payen.

Johnson.

Playfair and Lankester.

Boussin-gault.

Mitscher-licli.

Average of several other

Analyses.

Fat (Cocoa-Butter) . .

53.10

52.00

51.00

50.00

44.00

45.00

50.00

Albuminoid Substances

Albumin............

Fibrin

18.70

20.00

20.00

20.00

13.00

18.00

Gluten

20.00

Extractive Matter . . .

Sugar.................................

0.60

Starch. . . . .

Gum. . . . . . .

10.91

7.75

10.00

22.00

7.00 6.00

6.00

14.00

10.00 8.00

Lignine ....

Cellulose. . . .

Woody Fibre. . . .

0.90

2.00

4.00

13.00

6.08

Coloring Matter . . .

2.01

traces

2.00

3.05

2.60

Water......

5.20

10.00

5.00

5.00

11.00

5.06

6.00

Theobromine ....

2.00

2.00

2.00

2.00

1.02

1.50

Salts

4.00

4.00

4.00

Ash.......

3.05

3.60

Humic Acid ....

Parts unaccounted for .

1.43

9.14

0.30

Total

100.00

100.00

100.00

100.00

100.00

100.00

100.00

"The most abundant constituent of the seed," says Wanklyn, "is the fat, or cocoa-butter, which constitutes about one-half of the entire seed. Owing, no doubt, to this circumstance, the specific gravity of the seeds is less than unity, and they float on water. After being kept for some days in contact with the water some of the fat makes its escape, and the seeds sink to the bottom.

"I attach great importance to the determination of the ash. The following determinations of ash have been recently made in my laboratory: -

Percentage of Ash.

Common Trinidad ....

3.37

Very fine Trinidad ....

3.62

Fair, good, fine Trinidad .

3.64

Fine Granada......

3.12

Medium Granada.....

3.06

Caracas .......

4.58

Bahia (Brazil).....

3.31

Percentage of Ash.

Fine Surinam......

3.06

Fine Surinam (small) .

3.15

Mexican.......

4.27

Dominican ........................................

African ...............................................

2.68

The mean of the twelve being

3.39

"Separate determinations of the ash of the nib and the shell have also been made. In the nib of the Caracas the ash amounted to 3.95 per cent., whereof 2.00 was soluble in water, and 1.95 insoluble in water.

In the nib of the Mexican seeds the ash was found to be 2.59 per cent., whereof 0.89 was soluble, and 1.70 insoluble, in water. The shell (which, as mentioned above, formed only a very small portion of the entire seed) is much richer in mineral matter or ash. I have found as much as 7.81 per cent. of ash in the shell. The composition of the ash of the shell is very different from that of the nib; whilst the ash of the shell is rich in carbonates that of the nib is almost devoid of carbonates.

"A very careful analysis of the ash of the entire seed has been recently made by my friend, Mr. Wm. Bettel, in my laboratory. The results are as follows : - .

" Composition of ash of the entire seeds (Caracas), -

Potash K2 O.......

29.81

Chloride of Sodium Na Cl .

6.10

Peroxide of Iron Fi2 O3 . . .

1.60

Alumina Al2 O2

Lime Ca 0.......

7.72

Magnesia Mg O......

7.90

Phosphoric Acid P2 O5 ...

24.28

Sulphuric Acid S O3 . . .

1.92

Carbonic Acid C O2 .

0.98

Silica Si O2 ......................................

Sand .........................

99.86

"From this analysis it is apparent that the main constituent of the ash is phosphate of potash, and that there is almost total absence of carbonates. The ash of the shell being, as has been said, highly charged with carbonates, it follows that, in obtaining the ash of the entire seed, we cause the phosphates of the nib to decompose the carbonates of the shell, and so obtain an ash devoid of carbonates.

"The large proportion of phosphate of potash in cocoa (certainly not far from one per cent, in the seed of good quality) is worthy the attention of the physician, and no doubt gives an especial value to a dietary consisting largely of cocoa. It will further be observed that the fine kinds of cocoa-seeds are rich in phosphate of potash.....

"Mixtures of cocoa with starch and sugar have long been perfectly legitimate, provided no deception as to the strength in cocoa be practised."

In conclusion he says: "The preparations of cocoa constitute food rather than drink, being highly nutritious in every sense of the term. The fat present in cocoa - viz., the cocoa-butter - appears to be of a particularly available description. It is said never to become rancid, and merits an elaborate examination. Whether it be owing to peculiarities in the fat of cocoa, or whether it be the theobromine that is particularly efficient, certain it is that cocoa will sometimes nourish when nothing else will, and cocoa is occasionally invaluable to the physician."