The breasts in cylinder machines are usually made with removable steel ribs; but in Brazil, Nicaragua, and other countries, where, owing to the short season and scarcity of labor, the planters have to pick, simultaneously, green, ripe, and over-ripe (dry) cherries, rubber breasts are used. [Illustration: NIAGARA POWER COFFEE HULLER] [Illustration: MCKINNON'S GUARDIOLA COFFEE DRIER] [Illustration: THE SQUIER-GUARDIOLA COFFEE DRIER, WITH DIRECT-FIRE HEATER] [Illustration: BRITISH AND AMERICAN COFFEE DRIERS--GUARDIOLA SYSTEM There are numerous makes of coffee driers based upon the original invention of Jose Guardiola of Chocola, Guatemala. In the two illustrated above both direct-fire heat and steam heat may be utilized] The disk pulper (the earliest type, having been in use more than seventy years) is the style most generally used in the Dutch East Indies and in some parts of Mexico. The results are the same as those obtained with the cylindrical pulper. The disk machine is made with one, two, three, or four vertical iron disks, according to the capacity desired. The disks are covered on both sides with a copper plate of the same shape, and punched with blind punches. The pulping operation takes place between the rubbing action of the blind punches, or bulbs, on the copper plates and the lateral pulping bars fitted to the side cheeks. As in the cylinder pulper, the distance between the surface of the bulbs and the pulping bar may be adjusted to allow of any clearance that may be required, according to the variety of coffee to be treated. [Illustration: ANOTHER AMERICAN GUARDIOLA DRIER] Disk pulpers vary in capacity from 1,200 pounds to 14,000 pounds of ripe cherry coffee per hour. They, too, are made in combinations employing cylindrical separators, shaking sieves, and repassing pulpers, for completing the pulping of all unpulped or partially pulped cherries. _Fermentation and Washing_ The next step in the process consists in running the pulped cherries into cisterns, or fermentation tanks, filled with water, for the purpose of removing such pulp as was not removed in the pulping machine. The saccharine matter is loosened by fermentation in from twenty-four to thirty-two hours. The mass is kept stirred up for a short time; and, in general practise, the water is drawn off from above, the light pulp floating at the top being removed at the same time. The same tanks are often used for washing, but a better practise is to have separate tanks. Some planters permit the pulped coffee to ferment in water. This is called the wet fermentation process. Others drain off the water from the tanks and conduct the fermenting operation in a semi-dry state, called the dry fermentation process.