(the Phylax device illustrated at the top
of this page) the "art" consists in controlling the flow of the boiling
water by means of the number and spacing of the holes in the
water-spreader, so as to restrict the volume and the speed, to effect a
quick initial extraction; and then, by means of a new spacing of holes
in the infuser, retarding the drip "to attain a prolonged extraction of
the tannin and other elements of slow extraction and combining the
liquids obtained during the initial and subsequent stages of the brew
for attaining a balanced liquid extract."

[Illustration: HOW THE TRU-BRU POT OPERATES]

Muller's "art" (the apparatus is described in chapter XXXIV) consisted
in so supplying and supporting the ground coffee in an urn that it is
never again subjected to the "decoction" after having been exposed to
the air and steam following the first application of the water.

In 1920, William G. Goldsworthy, San Francisco, was granted a United
States patent on a process for preparing the beans for making the
beverage. The process consisted of grinding the raw dried beans; then
packing the ground product in non-combustible and non-soluble porous
containers, which are securely closed to keep them unimpaired while the
contained coffee is being roasted; and, after cooling, sealing them with
gelatine. To brew, container and contents are dropped into a cup of hot
water.

[Illustration: COFFEE-MAKING DEVICES USED IN THE UNITED STATES

1--Marlon Harland Pot; 2--Universal Percolator; 3--Galt Vacuum Process
Coffee Maker; 4--Universal Electric Urn; 5--English Coffee Biggin
(Langley Ware); 6--Universal Cafenoira (Glass Filter); 7--Vienna
(Bohemian or Carlsbad) Coffee Machine; 8--Tru-Bru Pot; 9--Tricolator;
10--Manning-Bowman Percolator; 11--Blanke's Sanitary Coffee Pot;
12--Phylax Coffee Maker; 13--Private-Estate Coffee Maker; 14--American
French Drip Pot; 15--Kin-Hee Pot; 16--Silex Opalescent Glass Filter;
17--French Drip Pot (Langley Ware).]

This brief review of the evolution of coffee brews shows that coffee
making started with boiling, and next became an infusion. After that,
the best practise became divided between simple percolation and
filtration, which have continued to the present time. Boiling has also
continued to find advocates in every country, even in the United States,
where it seems to die hard, no matter how much is done to discredit it.
Percolation devices are subdivided into the simple drip pots and th