114 NUTRITIVE PLANTS. 



bottom pierced with many small holes, so as to form a strainer ; and 

 a proper quantity of boiling hot water being poured cautiously on 

 this layer of coffee in powder, the water penetrates it by degrees, 

 and after a certain time begins to filter through it. This gradual 

 percolation brings continually a succession of fresh particles of pure 

 water into contact with the ground coffee j and when the last portion 

 of the water has passed through it, every thing capable of being dis- 

 solved by the water will be found to be so completely washed out of 

 it, that what remains will be of no kind of value. 



" It is however necessary to the complete success of this ope- 

 ration, that the coffee should be ground to a powder sufficiently 

 fine. 



" In order that the coffee may be perfectly good, the stratum of 

 ground coffee, on which the boiling water is poured, must be of a 

 certain thickness, and it must be pressed together with a certain de- 

 gree of force. If it be too thin, or not sufficiently pressed together, 

 the water will pass through it too rapidly ; and if the layer of ground 

 coffee be too thick, or if it be too much pressed together, the water 

 will be too long in passing through it, and the taste of the coffee will 

 be injured. 



The author recommends as of importance that the surface of the 

 coffee be rendered quite level after it is put into the strainer, before 

 any attempt is made to press it together, that the water in perco- 

 lating may act equally on every part. For this purpose he uses the 

 following contrivance : if The circular plate of tin, with a rod 

 fastened to its centre, which serves as a rammer for pressing down 

 the ground coffee, has four small projecting square bars, of about 

 one-tenth of an inch in width, fastened to the under side of it, and 

 extending from the circumference of the plate to within about one 

 quarter of an inch of its centre. On turning this plate round its 

 axis, by means of the rod which serves as a handle to it, (the rod 

 being made to occupy the axis of the cylindrical vessel,) the pro- 

 jecting bars are made to level the ground coffee ; and after this has 

 been done, and not before, the coffee is pressed together. 



" This circular plate is pierced by a great number of small holes, 

 which permit the water to pass through it, and it remains in the cy- 

 lindrical vessel during the whole of the time that the coffee is making. 

 It reposes on the surface of the ground coffee, and prevents its being 

 thrown out of its place by the water which is poured on it. The 



