Stores.—Though there is no necessity for curing the coffee, and it may be hulled at once, if desired, the exigencies of climate 'render a properly constructed store one of the greatest desiderata. The characteristic of the store must be dryness combined with security, hence galvanized iron forms the best material. It is generally of two storeys ; the lower floor is sometimes boarded or asphalted, but the upper is always so made as to admit of free circulation of air through the coffee placed on it. This object may be attained by laying wire gauze, or coir matting, over reepers about lin. apart. Abundant ventilation must be provided. It will be necessary to watch for any signs of heating ; and immediately on their appearance, the coffee must be turned over thoroughly.
An improved form of store is that built on the Cleriehew principle. The floor of the upper storey, constructed as in the former case, rests on joists running lengthwise of the building. A ceiling is provided for the lower storey, by tacking to the joists, cloth which has been well soaked in boiled rice-water and whitewash, to render it air-tight ; continuous air passages are thus made beneath the floor. About 10 ft. of one end of the lower apartment is partitioned off, and its sides are made as nearly as possible air-tight. It has, no ceiling other than the floor above, so that the passages all open into it. In au opening in the wall of this chamber, a pair of large revolving fans are placed. Their rapid revolution draws a continuous current of air from tbe inside, and therefore through the coffee itself. In this way, dried parchment can be kept in perfect condition, without any turning over. By using heated air on the same principle, coffee may be housed while. still only partially dry, and yet not suffer fermentation.
Bulling, or Peeling.—This operation consists in the removal of the " parchment " and the " silver skin." The beans must be again exposed to the sun, for a. period which it is difficult to define. Some say that they should be dried till they resist the pressure of the thumb-nail ; but there is really no infallible test, as no two samples are exactly alike. It needs much experience to prevent loss of weight by over-drying, or of colour by under-drying. 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 2 in. 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 15 ft. in diameter should turn out 12 cwt. market coffee an hour ;
4i bush. good parchment coffee should give 1 cwt. clean coffee. The appearance of the coffee imme diately after hulling is very light-coloured ; but it soon assumes horn-green tint, which it will retain unless exposed to damp, when it becomes dingy or mottled grey, and is classed as " country damaged." An apparatus for peeliog and polishing parchment cuffee, combined with one for hulling dry cherry coffee, is shown in Fig. 506. The two parts may be disengaged and worked separately. An improved machine by which coffee of all grades may be hulled, scoured, and cleaned, and different kinds and grades of coffee may be mixed, and turned out with uniform appearance, has been Patented by Patrick McAuliffe, of New York. Its operation is continuous, and it is said to create no dust.
Winnowing.—The peeled coffee, as it comes from the huller in company with the detached skins, is submitted to the influence of a fan, whose force must be so adjusted that it will effectually remove the skins without carrying off any coffee.
Sizing.—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 subsequent roasting process more equable in its effect. Formerly, the sizing was performed by hand garbling or picking ; but it is now the custom to employ a " separator," as shown in Fig. 507. It consists of an inclined, revolving, cylinchical aieve c, formed of perforated sheet iron, or steel wires, and divided into sections of different meshes. The coffee is fed in at the hopper a, which is furnished with a regulator and an internal worm, for the purpose of distributing it equally, while a revolving brush b prevents the meshes being choked. Sand and dust pass through the first section, and fall into the space d, small and broken beans are delivered at e, sound coffee escapes into f, the beat and largest beans are caught at g, and the pea-berry rolls freely out at the end h. Another form of separator, known as Penney's, of Lincoln, is made adjustable, so that the gauges can be modified to suit the variations to which the crop is liable in different seasons. It ia often fitted with a fan. By the use of these separators or sizera, the labour of garbling is reduced to merely picking out any stray foreign substances and unsound beans ; the broken beans, or " triage," must also be separated by baud from the dust.