EVAPORATION OF FRUITS. 15 



into the wall at either end. The salts that make the drying floor 

 proper are of whitewood or basswood, 1-J inches thick, 1^ inches 

 wide on the upper side, and three- fourths of an inch on the side next 

 the joist. In cross section they are keystone shaped. They are placed 

 one-fourth of an inch apart with the narrow side down, in order that 

 the openings between them may not be clogged with material lodging 

 in them. ' The floor strips should run at right angles to the side of 

 the kiln containing the door, so that it will be easy to handle the 

 product with shovels. Basswood or whitewood is used for making 

 kiln slats, for the reason that these woods do not warp or split under 

 heat and are free from resins or other constituents which could give 

 foreign odors or tastes to the product. After the floor is in place it 

 is oiled three times at intervals of a week with lard oil, paraffin oil, 

 or a mixture of equal parts tallow and boiled linseed oil, applied very 

 hot, in order thoroughly to impregnate the slats. This prevents stick- 

 ing of the fruit. After the kiln is in use, a few oilings each season 

 will keep it in good condition, but it should be thoroughly scrubbed 

 with strong hot soapsuds twice a week during the season. 



THE KILN-DRYING PLANT. 



Several individual kilns constitute a drying plant. As it is neces- 

 sary to have enough drying capacity to keep the machinery and help 

 employed, the number of ldlns in a plant varies, but economic con- 

 siderations would generally forbid the construction of a plant having 

 less than four kilns, since installations of power-driven equipment in 

 a smaller plant would be almost as expensive as in a four-kiln plant. 

 A plant of this size is large enough to keep the operators bus}^, and 

 plants larger than this increase the fire risk without adding much to 

 the economy. A plan sometimes followed when a larger capacity 

 than is offered by the four-kiln plant is desired is to erect two sets, 

 separated by a space of 75 to 100 feet, with an overhead bridge con- 

 necting them. One set of machinery and one workroom serve for 

 both, yet the fire risk is considerably reduced. 



Location of the plant. — The drying plant is, of course, located near 

 extensive orchards. Each 20 by 20 foot kiln will evaporate from 100 

 to 150 bushels of apples every 24 hours, a four-kiln plant operated 

 continuously for a working season of 60 days evaporating 20,000 or 

 25,000 bushels of apples if peels and cores are also dried, or a some- 

 what larger quantity if these are disposed of in other ways. If the 

 venture is to be profitable, sufficient fruit must be available to keep 

 the plant busy for the maximum period. 



Arrangement of the plant. — When a four-kiln unit is used the kilns 

 are usually arranged in a row with the work and storage rooms 

 along one side. The first-floor plan of such a plant is shown in 

 Figure 4. The structure is 80 feet long and the kiln portion 20 feet 

 wide. The workroom portion is 17^ feet wide and 80 feet long. The 

 furnace floor is dirt at the ground level, while the workroom floor is 

 on top of the foundation. Air inlets in the outer wall permit the air 

 to pass freely beneath the workroom floor to the air inlets of the 

 furnace rooms. Steps lead clown from the workroom to the furnace 

 room. Usually one end of the workroom is partitioned off and used 

 as an office, for supplies, or sometimes as bins. Frequently the bins 



