15 



The difficulties to be contended witk in arranging for the cold 

 storage of vegetables may be illustrated by the following case. 



An insulated storage room of about 6000 cubic feet capacity 

 was fitted with a refrigerating machine, which easily reduced the 

 air in the room, when empty, to a temperature of 2T^ F* 

 — 3^ C). A temperature of 35*^ F. (2^ C.) was required, and it 



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trial was then made as to storag-e. Six tons of vegetables* were 

 put into the room, and the temperature started at 59*^ F. 

 (15^ C), but the machine was only able to reduce this to 50^ F. 

 (10^ C.) in 10 hours. The refrigerator was then stopped, and 

 in 12 hours the temperature was 59*^ F., and after 15 hours 

 more it stood at 66^ F. (19*^ 0.)- The air, moreover, was found 

 to be badly vitiated by carbonic acid. The final rise of tempera- 

 ture was due to the respiration of the vegetablesf and not tu 

 conduction through the walls, since the outside temperature 

 during the last 24 hours had not been higher than 52° F. 

 (11^ C.), having varied between this and 45° F. (7° C). 



In another trial the machine was started first, and the tem- 

 perature was reduced to 3S^ F. Then two and a half tons of 

 cabbage and spinach were put into the store. The temperature 

 was raised hy this to 48° F., and after an hour with the machine 

 still running it rose to 49° F, After five hours' run it stood at 

 45° F., and refused to go lower. 



In this case the free air in the storage-chamber was well circu- 

 lated. The unsuccessful result indicates that the vegetables 

 required to be less crowded, or to be cooled in small 

 before being brought into the store. The air must have been a 

 good deal entangled among the vegetables, so that convection 

 currents in the interior of the mass in each box would be slow, 

 and consequently the loss of heatj in this way was not rapid 

 enough to out-balance the heating due to respiration. Had the 

 vegetables been cooled before being placed in the store-room, 

 their respiration and self-heating would have been slow, and the 

 refrigerating arrangements might perhaps have been able to 

 deal with them efficiently, though unable to cope with the com- 

 bined task of cooling the substance of the vegetables, and also 

 removing the heat generated by respiration at or near the starting 

 temperature. § The entanglement of air and consequent diffi- 

 culty of cooling would probably be much greater in a box of 

 spinach, for instance, than in a box of the same dimensions con- 

 taining fair-sized rounded fruit such as apples or oranges. 



It can be readily understood that the matter of cold storage of 

 fruit and vegetables is not a simple one. The treatment required 

 bv different kinds of fruit or vegetables may vary considerably as 



o 



* In boxes. n t 



t The result in this trial was probably almost entirely due to ordinary 

 respiration, though a small proportion may represent increased respiration 

 of cut and bruised surfaces. A little bacterial action may possibly hiive 

 begun, and contributed slightly to the rise in temperature. 



X To the refrigerated air, 



§ This refers to vegetables badly placed for cooling, not to those well 



exposed to the refrigerated air. 



