10 'Nov., 1917.] Evaporation of Apples. 671 



EVAPORATION OF Ari'LES.* 



By J. S. Caldwell, Fruit By-Productn Specialist, State College of 

 Washington Agricultural E.rperiment Station. 



(Continued from page 607.) 



IIeatinq Appakatus. 



Unfortunately there is at present no furnace on the market which 

 can be reeouimeiuled for use iu evaporators. The " hop stoves " gene- 

 rally used in hop kilns are of good size, but are too light in construction 

 to stand the continuous firing at utmost capacity for periods of 40 to 60 

 days necessary in an apple kiln. The large cast iron furnace weighing 

 1,500 to 2,000 lbs. each, universally used in Eastern evaporators, are 

 especially designed for burning hard coal. Soft coal cannot be used in 

 such a furnace, as the pipes promptly become clogged, while the opening 

 of the door in firing permits the escape of dense clouds of smoke and 

 soot, covering the fruit with black flecks, which completely ruin it. Since 

 the prices of hard coal entirely prohibit its use, furnaces of the prevailing 

 types in use in the East are not available to the North-western eva])orator, 

 who is restricted to wood as the only fuel which he can successfully and 

 economically use in hi,? kilns. 



One or two makers of evaporator machinery make heavy, durable cast 

 iron furnaces, intended to be fired with wood, and these are in successful 

 use in some sections of the United States and Canada. All such furnaces 

 with which the writer is acquainted, however, have the serious defect 

 that the fire-boxes are at most 36 to 42 inches in length, and not more 

 than 12 inches in height, while the door is usually 10 x 10 inches. Four- 

 foot cord wood must be cut in two, and the larger pieces split, which 

 entails considerable expense, while the fire-box cannot be properly filled 

 with the resulting 2-foot lengths. Consequently, the fires demand con- 

 stant attention, and the temiperaturos produced fluctuate considerably. 

 If some foundry centrally located in the i^orth-west would put upon the 

 market a heavy, well made, durable wood-burning furnace, having a 

 fire-box long enough to take 4-ft. wood, and at least 24 inches in width, 

 with doors 20 x 24 inches, it would find general favour. Cord woo<l 

 could be used as it comes from the forest, and it would be relatively easy 

 to maintain a constant temperature Avith a minimimi of attention. It 

 is hoped that such a furnace may soon be placed on the market. 



The most satisfactory source of heat is a well built brick or stone 

 furnace, properly lined with the best quality of fire brick. Such a 

 furnace should be at least 4 feet wide, and deep enough to take wood in 

 S-ft. lengths of any size that one man can readily handle. If the walls 

 are properly laid with a good quality of mortar, such a furnace is prac- 

 tically everlasting, except that the fire brick lining will need repairs 

 and partial replacement every second season, while the first sections of 

 pipe will scarcely stand more than one year's use. 



The piping of the furnace is extremely important, since the operator 

 must depend upon the arrangement of his pipes both for utilization of 

 the heat produced and for its uniform distribution to the drying floor. 



• Reprinted from a Bulletin issued by the State College of Washington Agricultural Experiment 

 Station. 



