d out by a
Michigan coffee packer,[333] it was discovered that a mixture of a very
fine with a coarse grind gives the best results in the cup. It was also
determined that coarse ground coffee loses its strength more rapidly
than the medium ground; while the latter deteriorates more quickly than
a fine ground; and so on, down the scale. His conclusions were that the
most satisfactory grind for putting into packages that are likely to
stand for some time before being consumed is a mixture consisting of
about ninety percent finely ground coffee and ten percent coarse. His
theory is that the fine grind supplies sufficiently high body
extraction; the coarse, the needful flavor and aroma. On this irregular
grind a United States patent (No. 14,520) has been granted, in which the
inventor claims that the ninety percent of fine eliminates the
interstices--that allow too free ventilation in a coarse ground
coffee--and consequently prevents the loss of the highly volatile
constituents of the ten percent of coarse-ground particles, and at the
same time gives a full-body extraction.

_Making and Filling Containers_

As stated before, a large proportion of the coffee sold in the United
States is put up into packages, ready for brewing. Such containers are
grouped under the name of the material of which they are made; such as
tin, fiber, cardboard, paper, wood, and combinations of these materials,
such as a fiber can with tin top and bottom. Generally, coffee
containers are lined with chemically treated paper or foil to keep in
the aroma and flavor, and to keep out moisture and contaminating odors.

As the package business grew in the United States, the machinery
manufacturers kept pace; until now there are machines that, in one
continuous operation, open up a "flat" paper carton, seal the bottom
fold, line the carton with a protecting paper, weigh the coffee as it
comes down from an overhead hopper into the carton, fold the top and
seal it, and then wrap the whole package in a waxed or paraffined
paper, delivering the package ready for shipment without having been
touched by a human hand from the first operation to the last. Such a
machine can put out fifteen to eighteen thousand packages a day.

Another type of machine automatically manufactures two and three-ply
paper cans such as are used widely for cereal packages. It winds the
ribbons of heavy paper in a spiral shape, automatically gluing the
papers together to make a can