wing the size and form of the cells as well as the drops
of oil contained within their cavities. Drawn with the camera lucida,
and magnified 140 diameters.

A fragment of roasted coffee under the microscope. Drawn with the camera
lucida, and magnified 140 diameters.]

[Illustration: BOGOTA, GREEN

Longitudinal--Magnified 200 diameters]

[Illustration: BOGOTA, GREEN

Cross Section--Magnified 200 diameters]

[Illustration: BOGOTA, GREEN

Tangential--Magnified 200 diameters]

[Illustration: BOGOTA, ROASTED

Tangential--Magnified 200 diameters]

[Illustration: GREEN AND ROASTED BOGOTA COFFEE UNDER THE MICROSCOPE

These pictures serve to demonstrate that the coffee bean is made up of
minute cells that are not broken down to any extent by the roasting
process. Note that the oil globules are more prominent in the green than
in the roasted product]

CHAPTER XVII

THE CHEMISTRY OF THE COFFEE BEAN

_Chemistry of the preparation and treatment of the green
bean--Artificial aging--Renovating damaged
coffees--Extracts--"Caffetannic acid"--Caffein, caffein-free
coffee--Caffeol--Fats and oils--Carbohydrates--Roasting--Scientific
aspects of grinding and packaging--The coffee brew--Soluble
coffee--Adulterants and substitutes--Official methods of analysis_

By Charles W. Trigg

Industrial Fellow of the Mellon Institute of Industrial Research,
Pittsburgh, 1916-1920

When the vast extent of the coffee business is considered, together with
the intimate connection which coffee has with the daily life of the
average human, the relatively small amount of accurate knowledge which
we possess regarding the chemical constituents and the physiological
action of coffee is productive of amazement.

True, a painstaking compilation of all the scientific and
semi-scientific work done upon coffee furnishes quite a compendium of
data, the value of which is not commensurate with its quantity, because
of the spasmodic nature of the investigations and the non-conclusive
character of the results so far obtained. The following general survey
of the field argues in favor of the promulgation of well-ordered and
systematic research, of the type now in progress at several places in
the United States, into the chemical behavior of coffee throughout the
various processes to which it is subjected in the course of its
preparation for human consumption.

_Green Coffee_

One of the few chemical investiga