92 THE RESPIRATION OF APPLES. 



Carbonic acid exhaled by 1 kilogram f)f apples for 1 hour at different 

 temperatures: 



50^ Fahrenheit. 



March 15, 6 hours, 13 6 milligrams. 



March 16, 6 hours, 13. 6 milligrams. 



March 18, 6 hours, 12. 5 milligrams. 



32° Fahrenheit. 

 March 21, 6 hours, .5.7 milligrams. 



March 22, 6 hours, 5.3 milligrams. 



March 23, 6 hours, 4.0 milligrams. 



March 24, 6 hours, 5.3 milligrams. 



68° Fahrenheit. 

 March 2.5, S hours, 21.9 milligrams. 



March 28, 6 hours, 21.2 milligrams. 



March 31, 6 hours, 22 5 milligrams. 



The average rate of exhalation of carbonic acid for one 

 kilocram of apples per hour was 13.2 milligrams at 50 

 degrees, 5.2 milligrams at 32 degrees and 21.9 milligrams 

 at 68 degrees. 



It will be seen on comparing the average rates of 

 exhalation of carbonic acid at the different temperatures, 

 that in pas.sing from melting ice (32°) to cellar tem- 

 peratures (45° to 50°) the rate nearly triples, and in 

 passing from the medium temperature to summer tem- 

 peratures the rate doubles. 



Since the breathing out of carbonic acid is an indication 

 of the rate of chemical change within the fruit, it follows 

 that changes of composition must take place from four to 

 six times as fast at summer temperatures as in cold storage 

 and from two to three times as fast in cool cellars as in 

 cold storage. 



These increases in rate are in agreement with the laws 

 of chemical action, as the speed of such reactions is found 

 to double and sometimes to triple when the temperature is 

 raised 18 degrees Fahrenheit (10 degrees Centigrade). 



There is a practical application of this law to be made to 

 the care of fruit especially at apple picking time. 



It is frequently the case that warm days with tempera- 

 tures of 70 depTPos occur in October and sometimes con- 

 tinue for a considerable period. Fancy apples intended 

 for long keeping in cold storage should be cooled as soon 

 as possible and kept cold. The breathing process is at the 

 expense of cell contents and must weaken the keeping qual- 

 ities as it goes on. And this destructive action is from four 

 to six times as fast out of cold storage as inside it. 



Another fact in connection with the respiration is im- 

 portant. It is not stopped in cold storage, but simply 

 slowed. Apples cannot be kept indefinitely but keep about 

 twice as long in cold storage as in a cool cellar. 



