OUTLINE OF EXPEKIMENTS. 15 



THE AIR-CIRCULATING SYSTEM. 



Iii the indirect or air-circulating system the air in a well-insulated 

 room, which is sometimes called a coil room or a "bunker room," is 

 first cooled, either by the direct-expansion or by the brine-circulating 

 S3 T stem. The cold air of the coil room is then forced through ducts 

 to the storage rooms. After passing through the storage rooms it is 

 returned by ducts to the coil room to be recooled and purified and to 

 begin the circuit anew. 



There are man}^ modifications in the details of these systems when 

 applied to storage houses, but as this publication does not deal prima- 

 rily with the engineering side of refrigeration it is the purpose to set 

 forth approximately the fundamental principles on which the most 

 common storage systems are based rather than to discuss their appli- 

 cation or their respective merits. 



OUTLINE OF EXPERIMENTS IN APPLE STORAGE. 



An outline of the apple storage experiments of the United States 

 Department of Agriculture is presented here. The following problems 

 have been under investigation during two apple seasons: 



(1) A comparative test of the keeping qualit}^ of a large number 

 of varieties grown in different regions and of the same varieties grown 

 under different conditions and in different localities. 



The fruit has been stored in closed 50-pound boxes in a temperature 

 of 31° to 32° F. One-half of the fruit in each box has been wrapped 

 in paper. 



(2) A determination of the influence of various commercial methods 

 of apple handling on the keeping quality of the most important varie- 

 ties in the leading apple-growing regions of the eastern United States. 



Each variety has been picked at two different degrees of maturity: 

 First, when nearly grown but only half to two-thirds colored, or about 

 the time when apples are usually picked; second, when the fruit was 

 fully grown and more highly colored, but still hard. In each picking 

 the fruit was separated into two lots, representing the average of the 

 lightest and of the darkest colored or most mature specimens. 



Part of the fruit of each series was sent to storage as soon as picked. 

 A duplicate lot was held two weeks in the orchard or in a building, 

 either in piles or protected in packages, before it was sent to storage. 



Comparative tests have been made to determine the efficiency of 

 different kinds of fruit wrappers on the keeping of the fruit, and 

 observations on the behavior of the fruit in closed and ventilated 

 packages have been recorded. 



(3) A determination of the influence of various cultural and other 

 conditions of growth on the keeping qualit}^ of the fruit. 



Comparison has been made with the same variety from heavy clay and 



