DRYING APPARATUS, ETC. 167 



the stove is covered. A sliding overhung door closes the 

 apparatus, and makes an hermetically sealed chamber. 

 The interior of this chamber is fitted with a number of 

 steam-heated shelves of special grid type so constructed 

 that the steam must equally search every portion of the 

 shelf. Their method of action is also special to this make 

 of apparatus, inasmuch as the steam joint is outside the 

 stove and not inside as in other makes. This remedies 

 the liability to leakage and consequently the atmosphere 

 in the stove itself is a particularly dry one, and this conduces 

 more than anything to a rapid even drying. These steam- 

 heated shelves are all controlled by one valve, steam being 

 admitted equally to all of them, and at the same time. 

 This may be exhaust steam, and where such is available 

 forms a further economy. The vacumn is produced by 

 means of a steam or power-driven vacuum-pump absorbing 

 from 1 to 4 horse-power, according to the size. The vapour 

 which comes away from the stove is led in a single vapour 

 pipe to the condenser, which is a multitubular two-flow 

 condenser, where it is condensed by means of cold water, 

 and the water thus formed is conducted into the receiver, 

 which prevents moisture reaching the vacuum-pump. 

 The beans are usually placed on nets, or perforated trays, 

 and are then inserted between the steam-heated shelves, 

 so that they are heated from both above and below. It 

 is, of course, usual to prepare one set of trays to recharge 

 the apparatus the moment those which are being dried 

 are ready for removal. The time occupied varies from 

 two to six hours according to the state of the bean. 



(6) Kiln dryers. — Several dryers described by Preuss are 

 mentioned by Wright in his work " Cacao," page 135. In 

 Trinidad, Hoadley's apparatus, as depicted in Fig. 51, is 

 of the heated floor type. A plant was erected in Trinidad 

 and was seen working by the members of the West Indian 

 Agricultural Conference held in Trinidad in 1905, and was 

 described in the July issue of the Botanical Bulletin 

 (Trinidad) for that year. The building which contains the 

 apparatus is some 35 ft. square. In its upper chamber 



