684 " Journal of Agriculture, Victoria. [10 Nov., 1917. 



which is almost dry, and which consequently gives up only a small 

 fraction of the amount of moisture which the air is capable of carrying. 

 Thence the air rises through successive layers of fruit, each containing 

 more moisture than its predecessor, until finally, just before entering the 

 ventilator shaft, it passes over trays which have just been inserted. 

 The tunnel thus exactly reverses the method of the old tower evaporator, 

 in Avhieh fresh fruit was put in at the bottom, nearest the source of heat, 

 and the moist air driven from it through the trays of partially dried 

 fruit above. In such towers the air (jften had its temperature so much 

 lowered before reaching the top of the stack that a part of the moisture 

 carried by it was deposited upon the fruit in the upper trays. In the 

 tunnel this is entirely avoided, and the time required for drying is very 

 materially shortened, with a corresponding improvement in the quality 

 of the product. 



When the plant is operating, fires are kept going continuously in 

 the furnaces, and trays of fresh fruit are inserted at the upper end of 

 the tunnels as they are prepared. During the day, the tunnels will 

 usually be kept full to capacity by the replacement of the finished trays, 

 as rapidly as they are withdrawn, by trays of green fruit, which neces- 

 sitates the occasional shifting downward of the partially dried fruit to 

 make room at the top. In the afternoon, before the employees cease 

 work for the day, all other work may be stopped, and a sufficient number 

 of trays filled to replace those which will become dry during the night. 

 These are stacked near the tunnels. It is the duty of the night man to 

 keep up the fires, to remove such trays as become dry, to keep the 

 unfinished trays compactly together in the lower portion of the tunnel, 

 and to put in fresh fruit as room is made for it. This method has many 

 advantages; it prevents the overheating and scorching likely to occur 

 when the tunnels are gradually emptied during the night; it utilizes all 

 the heating value of the fuel burned, and it gives continuous operation 

 at full capacity, hence at a lower cost. 



Nothing will aid more in the rapid and economical drying of the 

 fruit than constant attention to the ventilation. The air-intakes into the 

 furnace room must be adjusted anew with every change in the force 

 and direction of the wind, and the damper in the ventilating shaft must 

 be at one time widely opeii, at another almost closed. The plant cannot 

 be left in charge of a man who is either careless or miintelligent, he 

 must understand clearly that it is just as much a part of his duty to 

 maintain a vigorous draught through the tunnel as it is to keep the tem- 

 peratures shown by the thermometers in the tunnels constant, and that 

 failure in either of these respects results in slower drying and an inferior 

 product of greater cost. Consequently, the kiln man should be the most 

 intelligent and capable employee about the establishment. If there is 

 any difi'erence, the best man should be selected as night man, since the 

 greater humidity and lower air temperatures prevailing at night make 

 the task of securing satisfactory drying during that period a very difficult 

 one. Once the kiln men are selected and put to work, they should be held 

 responsible for the management of the drying rooms, and no interference 

 by others tihould be attempted or tolerated. " Many cooks spoil the 

 broth " is a proverb never more true than when applied to the ventilating 

 and heating of an evaporator. 



(To he continued.) 



