WINNOWING AND SIZING. 97 



by over-drying, or of color by under-drying, but they 

 peel best while still warm. A variety of hullers have 

 been tried, but preference is commonly given to the old- 

 fashioned edge-runner mill, composed of a circular trough 

 with two large wheels revolving in it and suspended 

 about two inches from the bottom. The trough is one- 

 half to two-thirds filled with beans, which remain until 

 the grinding action of the revolving-wheels has separated 

 their skins, when they are let out by a lateral aperture. 

 A trough fifteen feet in diameter should turn out at least 

 1, 200 pounds of marketable coffee an hour, four bushels 

 of good parchment coffee yielding lOO pounds clean 

 coffee. The appearance of the coffee immediately after 

 hulling is very light colored, but it soon assumes a fern- 

 green hue, which it will retain unless exposed to damp, 

 when it becomes dingy or mottled-gray, and is classed 

 as " country damaged." 



AVI]VIVOi;VIT^G A.]Vr> SIZIIVG. 



The peeled Coffee as it comes from the huller in com- 

 pany with the detached skins is submitted to the influ- 

 ence of a fan whose force must be so adjusted that it will 

 effectually remove the skins without carrying off the 

 Coffee. When the Coffee has been cleaned from the 

 skins, it is necessary to separate it into various sizes for 

 market, chiefly with the object of rendering the subse- 

 quent roasting process more equable in effect. Formerly 

 the sizing was performed by hand-picking, but it is now 

 the custom to employ a machine called a " separator," 

 which consists of an inclined, revolving cylindrical sieve 

 formed of perforated sheet-iron or steel wires, and divided 

 into sections of different meshes. The Coffee is fed in at 

 the hopper, which is furnished with a regulator and an in- 

 ternal worm for the purpose of distributing it equally, 



