At the annual convention of the National Coffee Roasters Association,
November 2, 1921, Professor Prescott made a further report, in which he
stated that investigations on coffee brewing had disclosed that coffee
made with water between 185 deg. and 200 deg. was to be preferred to coffee
made with the water at actual boiling temperature (212 deg.), that the
chemical action was far less vigorous, and that the resulting infusion
retained all the fine flavors and was freer from certain bitter or
astringent flavors than that made at the higher temperature. Professor
Prescott announced also that the best materials for coffee-making utensils
were glass (including agate-ware, vitrified ware, porcelain, etc.),
aluminum, nickel or silver plate, copper, and tin plate, in the order
named[381].

The Joint Coffee Trade Publicity Committee's booklet on _Coffee and
Coffee Making_, issued in 1921, was very guarded in its observations on
grinding and brewing. It avoided all controversial points, but it did go
so far as to say on the general subject of brewing:

Chemists have analyzed the coffee bean and told us that the only
part of it which should go into our coffee cups for drinking is an
aromatic oil. This aromatic element is extracted most efficiently
only by fresh boiling water. The practice of soaking the grounds in
cold water, therefore, is to be condemned. It is a mistake also to
let the water and the grounds boil together after the real coffee
flavor is once extracted. This extraction takes place very quickly,
especially when the coffee is ground fine. The coarser the
granulation the longer it is necessary to let the grounds remain in
contact with the boiling water. Remember that flavor, the only
flavor worth having, is extracted by the _short_ contact of boiling
water and coffee grounds and that after this flavor is extracted,
the coffee grounds become valueless dregs.

The report contained also the following helpful generalities on coffee
service and the various methods of brewing in more or less common use in
the United States in 1921:

Although the above rules are absolutely fundamental to good Coffee
Making, their importance is so little appreciated that in some
households the lifeless grounds from the breakfast Coffee are left
in the pot and resteeped for the next meal, with the addition of a
small quantity of fresh coffee. Use