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in benzol was then twice treated with a little water, which had been cooled below 40° F. (4'4° C.), and on decanting the water the theobromine was left as a powder perfectly white and pure, with the exception of a trace of inorganic matter, which was estimated by ignition. As even the cold water in some instances dissolved out a little of the theobromine, it was found desirable to evaporate the water extract to dryness, and again treat with cold water, when a further small quantity of crystals was obtained. If the crude residue obtained by alcohol from the magnesia mixture were submitted to a nitrogen combustion with copper oxide, and the nitrogen found calculated into theobromine, a higher and probably more accurate percentage of alkaloids would be obtained.
Ash. The following table exhibits the percentage composition of the ash of cocoa nibs and husk :
ANALYSIS OF THE ASH OF COCOA NIBS AND HUSK.
It will be seen from the above analyses of the ash of the cocoa nib that the total amount of ash and of the several constituents of which it is composed, very closely correspond in the case of Nos. 2, 3, and 4. No. 1-the Guayaquil-has a preeminent position with regard to its total ash, and perhaps also in an equal degree in the amount of its phosphoric acid (P2O5), which forms practically one half of the entire ash and is equal to 179 per cent. on the whole cocoa kernel. The ash is distinguished by the small amount of chlorine, soda, and carbonates present, and it may also be remarked that the magnesia is from three to five times greater in quantity than the lime, a circumstance somewhat unusual in the ash of vegetable products.
The ash obtained from the husk is about three times the quantity found in the kernel of the cocoa from which the husk was derived. Though the phosphoric acid bears a lower proportion to the other constituents of the ash of the husk, yet in actual amount it is half as much again as the phosphoric acid in the same weight of the kernel. The potash alone in the husk is more than the average weight of ash obtained from the four varieties of the kernel.
TABLE SHOWING THE PERCENTAGE OF MOISTURE, AND OF TOTAL ASH IN VARIOUS Cocoas, WITH THE RELATIVE SOLUBILITY OF THE LATTER.
TABLE SHOWING THE PERCENTAGE OF ASH SOLUBLE AND INSOLUBLE IN WATER AND DILUTE HYDROCHLORIC ACID RESPECTIVELY.
A noteworthy feature in connection with the mineral matter of cocoa is the large proportion which is soluble even in cold water. Two cocoas were exhausted with cold water and the mineral matter in the filtrate estimated by ignition, with the following results:
It will thus be seen that, in using only the boiled extract of cocoa for dietetic purposes, nearly all the available mineral matter is obtained in solution.
ADULTERATION OF COCOA.
The practice has existed for many years of adding starch and sugar to cocoa in the manufacture of prepared or soluble cocoas, and so long as these preparations are not sold under the denomination of pure or unmixed cocoa, the admixture cannot strictly be called a form of adulteration.
As the proportion of fat in the natural cocoa has been found to disagree with many persons, a considerable popular demand has arisen for cocoas less rich in this constituent, and there appears to be little or no objection to the removal of, say, a moiety of the fat, which would still leave, in the case of most cocoas, at least 25 per cent.
Moisture 4'95 5'47 258 5'49 3952 4'40 2'60 I'44 Fat 24′94 16·86 22°76 28°24 23.98 29.60 51°77 22:08 29′50 Starch (added)... 19°19 24'70 17.56 none none none none 2'00 none Sugar (cane) 61.21 2303 29 23 32 20 Non-fatty Cocoa 27.89 23 74 24'90 66 27 72.50 66.00 45.63 1327 64°74
From the above analyses it will be seen that several of the
commercial cocoas consist of the powdered nibs only deprived of from 40 to 50 per cent. of their fat.
"Flake cocoa" contains the husk in a ground state.
As the husk contains more ash and extractive than the kernel, the presence of the former raises the proportion of the ash; and in cases where the quantity of ash is taken as a criterion of the value of a prepared cocoa, the husk gives an apparent increase in value.
The four mixed cocoas in Table 1 fairly represent the composition of the commercial articles of this class.
Some of the results of an analysis of a sample of Trinidad "nibs" are entered in Table 1 as a means of comparison, Trinidad cocoa being selected as, in chemical composition, it stands midway between the poorer and richer varieties of
It is said that the adulteration of cocoa has been practised by the addition of chicory, oxide of iron, ferruginous earth, chalk, sulphate of lime, etc. In recent years, however, there is little reason to believe that these substances have been added to cocoa.
In the examination of commercial cocoas the estimation of the fat and of the added starch and sugar will usually give an accurate idea as to the amount of cocoa contained in a sample. An indirect method of arriving at this result, and employed by some chemists, is to make a cold-water extract of the cocoa, estimate the dry extract and percentage of ash contained in it, and, by the adoption of certain standards for pure cocoa, by a simple calculation determine the proportion of genuine cocoa present. This method is beset with some difficulties, and these partly arise from the want of uniformity in the results obtained from different kinds of genuine cocoa, and from the presence of the husk, which gives more extractive and mineral matter to water than the nib, and therefore unduly increases these.
About three grams of the cocoa, and 200 cubic centimetres of water are taken. The cocoa is well rubbed up with a little of