Ferrnenting.—The " parchment " coffee, as it comes from the pulpers, is next submitted to a fermentation procees, to remove the saccharine matter, without which the beans would not dry. This operation is performed in a series of tanks whose capacity will vary with the eize of the estate, and which may be arranged as shown in Fig. 505. The pulpers are placed on a platform G, above the tanks, and in such a position that the pulped coffee can be run by water into the tanks, which must also be so situated that the coffee will always advance by the aid of running water, and may finally be conveniently conveyed to the drying ground, while the water and refuse run off. The amount of cistern accommodation neces sary for an eetate may be based on the allow ance of 1 oub. ft. for each bushel of cherry picked in one day. The tanks are seldom less than three in number—two receiving cisterns, each large enough for the greatest possible daily pick, and a third for washing the parch ment, nearly as large, superficially, as the other two combined. In the figure, A B are the washing tanks, 12 ft. 6 in. by 17 ft. 2 in. by 2 ft. deep, separated by a causeway 3i ft.
wide ; C D E I', the fermenting tanks, each 8 ft. by 18 ft. 9 in. by 2i ft. deep. These tanks are usually of brickwork, lined with cement or asphalt ; but wood is much better, because less cold. They all have a slight incline, to assist the drainage. The receiving tanks are provided at the lowest corner with a good-eized outlet fitted with a plug, and with a movable sieve of perforated zinc or woven wire, fine enough to keep back the coffee when draining off the water, but not so fine as to choke with the saccharine scum. The receiving cisterns are used alternately. All the coffee pulped in one day is allowed to remain in the receiving cistern until a slight fermentation has set in ; this occurs in twelve to eighteen hours in mild weather, but in cold weather it may take thirty to forty hours, or even more. There are two ways of conducting the ferrnentation—the dry, and the wet. The former consists in allowing the pulped berries to lie without water, the bottom of the tank being perforated, so as to drain off the liquid ; by the latter, the tank remains full of water. The dry system is the better, as long as care is taken to turn the mass, so that the fermentation shall be equal throughout ; the presence of water equalizes the fermentation, but retards it, and slightly injures the quality of the coffee. When the fermentation is not sufficiently prolonged, the beans will assume a yellowish colour— called "blanketty "—and will be difficult to dry, and liable to absorb moisture. When properly fer mented, the separation of the saccharine matters is easily effected in the washing tanks, to which the beans and a good supply of water are admitted. The washing cistern is provided with a eluice door J at the lowest corner. This door commonly measures 6 in. wide by 3 in. deep. The coffee is constantly agitated by a wooden scraper or rake, by which the light coffee and refuse rnatters float, and may be skimmed off. The dirty water flows off through a tail-cistern, provided with a grating to catch the skins and any stray parchrnent. The sound berries are placed in drain ing boxes to remove the excess of moisture, and are then transferred to the drying ground, with the least possible delay. Should the climate be uncertain, it will be necessary to provide for the emer gency of a succession of wet days, when drying cannot be proceeded with. Parchment coffee may be kept undried for a fortnight, without injury, by placing it in a cistern exposed to a continuous flow of cold water.
Drying.—The berries to be dried are spread out on a flat surface exposed to the heat of the sun. The material forming the drying ground, or " barhecue," varies greatly. Very commonly, the ground is levelled, aud then oovered with a kind of concrete. Sometimes asphalt is laid down ; but, besides being expensive, it is not sure to withstand the heat, and such surfaces are liable to crack and give way, if not very carefully drained. A very good plan is to lay down coir matting, on ground which has simply been made smooth and hard ; the advantages of this plan are its cheap ness, the ease with which extra ground can be requisitioned in case of need, and the use of the matting as a temporary covering in the event of a shower. Modifications of this method are to stretch coir or gunny cloth across wooden frames, or across trays with or without wheels. Shed accommodation must always be provided ready for the reception of the coffee at any moment. The beans must be constantly turned over, either by light rakes or by coolies' feet. The drying must be rendered equable, and must not proceed so rapidly as to crack the parchment before the bean is quite dry ; for this reason, the coffee should not be exposed too long to a strong sun for the first day or so. During the drying, it is gathered in each day while the sun is still hot, and will then con tinue to dry under cover. Every care must be taken to prevent heating, which may happen by prolonged drying in mild weather ; rather than permit this, the coffee should be returned to a tank, and kept washed with running water. If artificial drying can be effected, so much the better. An easy means of applying artificial heat is by passing an iron pipe, open at both ends, through a fire outside the store and below the level of the floor, continuing it into the store just beneath the floor. The heated air, passing upwards through the coffee, will carry off much of the damp. Revolving drying machines are also in the market. One of the best of these is Davey and Paxman's, originally intended for drying corn. It consists of cylinders, into which steam enters, and agitators arranged so that the coffee is impelled forwards, and caught up and rained down as the cylinder revolves. The central cylinder works in a steam jacket, outside which is a light casing of sheet iron, perforated at one end, so that air may be drawn through by a fan, to assist in the drying and to carry off the liberated moisture. This machine obviates the necessity for re spreading the coffee on the barbecues before hulling. Three days' thorough sunning usually suffices to render the coffee quite dry and brittle, iu which condition it is known as " parchment." As a rule, it is sent to port in this state, its further curing being left to the shippers ; for not only is considerable expenditure on buildings and machinery necessary for the purpose, but the experi ence gained in manipulating various parcels of coffee will enable those who make the subject a special study to bring the sample up to the best standard of appearance and keeping properties. Coffee is said to retain its colour better, if allowed to remain for several weeks in tLe parchment ; and its quality is said to continue to improve for months, and even years, the process being known as " curing." As, however, protracted curing causes great subsequent difficulty in removing the silver skin, coffee is never kept in the parchment longer than is compulsory.