tions of the growing tree is the
examination by Graf of flowers from 20-year-old coffee trees, in which
he found 0.9 percent caffein, a reducing sugar, caffetannic acid, and
phytosterol. Power and Chestnut[102] found 0.82 percent caffein in
air-dried coffee leaves, but only 0.087 percent of the alkaloid in the
stems of the plant separated from the leaves. In the course of a
study[103] instituted for the purpose of determining the best
fertilizers for coffee trees, it developed that the cherries in
different stages of growth show a preponderance of potash throughout,
while the proportion of P_2_O_5 attains a maximum in the fourth month
and then steadily declines.

Experiments are still in progress to ascertain the precise mineral
requirements of the crop as well as the most suitable stage at which to
apply them. During the first five months the moisture content undergoes
a steady decrease, from 87.13 percent to 65.77 percent, but during the
final ripening stage in the last month there is a rise of nearly 1
percent. This may explain the premature falling and failure to ripen of
the crop on certain soils, especially in years of low rainfall.
Malnutrition of the trees may result also in the production of oily
beans.[104]

The coffee berry comprises about 68 percent pulp, 6 percent parchment,
and 26 percent clean coffee beans. The pulp is easily removed by
mechanical means; but in order to separate the soft, glutinous,
saccharine parchment, it is necessary to resort to fermentation, which
loosens the skin so that it may be removed easily, after which the
coffee is properly dried and aged. There is first a yeast fermentation
producing alcohol; and then a bacterial action giving mainly inactive
lactic acid, which is the main factor in loosening the parchment. For
the production of the best coffee, acetic acid fermentation (which
changes the color of the bean) and temperature above 60 deg. should be
avoided, as these inhibit subsequent enzymatic action.[105]

Various schemes have been proposed for utilizing the large amount of
pulp so obtained in preparing coffee for market. Most of these depend
upon using the pulp as fertilizer, since fresh pulp contains 2.61
percent nitrogen, 0.81 percent P_2_O_5, 2.38 percent potassium, and
0.57 percent calcium. One procedure[106] in particular is to mix pulp
with sawdust, urine, and a little lime, and then to leave this mixture
covered in a pit for a year before using. In addition to the