chapter XXXIV

. He was a coffee connoisseur; and as such was one of the first to advocate the use of cream as well as sugar for making an ideal cup of the beverage. He refers, though not by name, to De Belloy's percolation method and says, "Its usefulness is now universally acknowledged."

_A Few Definitions_

Just here, in order to assure a better understanding of the subject, it may be well to clear up sundry misconceptions regarding the words percolation, filtration, decoction, infusion, etc., by the simple expedient of definition.

A decoction is a liquid produced by boiling a substance until its soluble properties are extracted. Thus the coffee drink was first a decoction; and a decoction is what one gets today when coffee is boiled in the good old-fashioned way--as "mother used to make it."

Infusion is the process of steeping--extraction without boiling. It is extraction accomplished at any temperature below boiling, and is a general classification of procedure capable of sub-division. As generally and correctly applied, it is the operation wherein hot water is merely poured upon ground coffee loose in a pot, or in a container resting on the bottom of the pot. In the strictest sense of the term, an infusion is also produced by percolation and filtration, when the water is not boiled in contact with the coffee.

Percolation means dripping through fine apertures in china or metal as in De Belloy's French drip pot.

Filtration means dripping through a porous substance, usually cloth or paper.

Percolation and filtration are practically synonymous, although a shade of distinction in their meaning has arisen so that often the latter is considered as a step logically succeeding the former. Accomplishing extraction of a material by permitting a liquid to pass slowly through it is in fact percolation, whereas filtration of the resultant extract is effected by interposing in its path some medium which will remove solid or semi-solid material from it. Coffee-making practise has in itself so applied these terms that each is considered a complete process. Percolation is thus applied when the infusion is removed from the grounds immediately by dripping through fine perforations in the china or metal of which the device is constructed.

True percolation is not produced in the pumping "percolators" in which the heated water is elevated and sprayed over the ground coffee held in a metal basket in the upper part of the pot, the liquor being recirculated until a satisfactory degree of extraction has been reached. Rather, the process is midway between decoction and infusion, for the weak liquor is boiled during the operation in order to furnish sufficient steam to cause the pumping action.

Filtration is accomplished when the ground coffee is retained by cloth or paper, generally supported by some portion of the brewing device, and extraction effected by pouring water on the top of the mass, permitting the liquid to percolate through, the filtering medium retaining the grounds.

_Patents and Devices_

From the beginning, the French devoted more attention than any other people to coffee brewing. The first French patent on a coffee maker was granted in 1802 to Denobe, Henrion, and Rauch for "a pharmacological-chemical coffee making device by infusion."

In 1802, Charles Wyatt obtained a patent in London on an apparatus for distilling coffee.

The first French patent on an improved French drip pot for making coffee "by filtration without boiling" was granted to Hadrot in 1806. Strictly speaking, this was not a filtering device, as it was fitted with a tin composition strainer, or grid. It was very like Count Rumford's percolator announced six years later, as will be seen by comparing the two in