obtained in a
short time with a minimum of hydrolysis, oxidation, and loss of
caffeol; and if the infusion be consumed at once, or kept warm in a
contrivance embodying the double-boiler principle, the effects of
local overheating are avoided. Also, with the use of an appropriate
filter, a finer grind of coffee can be used than in the other
devices, without obtaining a turbid brew. All this works toward the
production of a desirable drink.

There are several devices on the market, some using paper, and some
cloth, as a filter, which operate on this principle and give very
good coffee. The use of paper presents the advantage of using a new
and clean filter for each brew, whereas the cloth must be carefully
kept immersed in water between brews to prevent its fouling.

Contrivances operating on the filtration principle have been
designed for use on a large scale in conjunction with coffee urns,
and have proven quite successful in causing all of the water to go
slowly through the coffee without channeling, thus accomplishing
practically complete extraction. The majority of urns are still
operated with bags, of which the ones with sides of heavier
material than the bottom obtain the most satisfactory results, as
the majority of the water must pass through the coffee instead of
out through the sides of the bag. Greatest efficiency, when bags
are used, is obtained by repouring until all of the liquid has
passed twice through the coffee; further repouring extracts too
much of the astringent hydrolysis products. The bags, when not in
use, should not be allowed to dry but should be kept in a jar of
cold water. The urns provided with water jackets keep the brew at
almost a constant temperature and avoid the deterioration incident
to temperature fluctuation.

COMPOSITION OF BREWS. The real tests of the comparative values of
different methods of brewing are the flavor and palatibility of the
drink, in conjunction with the number of cups of a given strength
which are produced, or the relative strengths of brews of the same
number of cups volume. Chemical analysis has not yet been developed
to a stage where the results obtained with it are valuably
indicative. Caffeol is present in quantities so small that no
comparative results can be obtained. "Caffetanni