26 BULLETIN 1413, U. S. DEPARTMENT OF AGRICULTURE 
bromine was determined), 3.2 per cent for one extracted cocoa, and 
1.6 and 2 per cent for the cocoa shells. Other work on cocoa prod- 
ucts has indicated that the caffeine amounts to only about 5 per 
cent of the total alkaloid present. 
PRACTICAL VALUE OF BY-PRODUCT COCOA CAKE 
One of the two manufacturers of mixed fertilizer, known to have 
used the ground cocoa cake in commercial mixtures, reported that 
it gave satisfaction as a conditioner and crude ammoniate filler. 
This use of the press cake corresponds to the use of ground cacao 
shells in the fertilizer industry. The function of such material is 
to absorb moisture, produce a good mechanical condition in the 
mixed goods, and furnish organic ammonia in a form which be- 
comes available gradually, thus insuring a more lasting supply of 
nitrogen. "When asked if the large proportion of fat present in the 
material used had caused any trouble, this manufacturer stated that 
he had had no complaints, but that relatively small quantities of 
the cocoa were used in his mixtures. 
The other user of cocoa cake as fertilizer material is one of the 
foremost concerns manufacturing complete fertilizers in the United 
States. This company, which uses ground cacao shells and dried 
solvent-extracted cocoa as " rough ammoniate " conditioners also, 
tried out the unextracted cocoa. The ground cake did not seem to 
be potentially as good a drying agent as the ground shells, but, 
of course, it supplied more organic nitrogen to the mixture. The 
selling price of the three cocoa by-products (ground shells, cake, 
and extracted cocoa) in the fertilizer trade is said to be based on 
the ammonia and potash content of the materials. The fertilizer 
concern mentioned was paying about the same price per unit of 
ammonia for cacao-shell meal and dried extracted cocoa as for 
" nitrogenous tankage," but considered the unextracted cake to be 
worth only about nine-tenths as much per unit of ammonia. A 
"unit" in the fertilizer trade is 1 per cent on a ton basis, or 20 
pounds. 
On this basis, under normal market conditions, the cocoa cake 
has a much higher value as fertilizer material than as fuel. As 
to the suitability of the cake for fuel, opinions of the manufacturers 
who have burned the product under their boilers differ markedly. 
There is ample testimony, however, to the effect that the relative 
fuel value of the cake, on paper, may be realized where the boiler- 
house engineer studies the character of the material as fuel and 
adapts his practices accordingly. At one large cocoa establishment 
there were loud protests from the engine room when use of the 
low-grade cake for fuel was discontinued because a more remunera- 
tive outlet for the product had been obtained. 
Utilization of by-product cocoa as a fertilizer material is also in 
competition with its uses as a feed stuff and as a source of the- 
obromine, therefore certain factors affecting its disposal through 
these channels are pertinent to this study. Feed mixers can afford 
to pay more than fertilizer manufacturers for the nitrogen in any 
organic material that they can use as a source of protein. Manu- 
facturers of mixed feeds commonly endeavor to include in a mixture 
several dissimilar concentrates for furnishing protein, thus supply- 
ing variety in the feed. It was to have been expected, therefore, 
