STUDIES OF CRANBERRIES DURING STORAGE. 



87 



For the Deterjiination of Rate of Respiration. 



The apparatus consisted of a respiration chamber into which air freed from any carbon 

 dioxide could be drawn, and from which the air could be conducted through a liquid which 

 would absorb all of the exhaled carbon dioxide carried along in the current. 



Respiration Apparatus. 



The respiration chamber was of tin and would hold about 3 quarts. It was open at the top 

 and was closed by a disk of tin which rested on a narrow shelf extending around the inner wall 

 a half inch below the top. The bottom was funnel-shaped with the outlet for the exhaled gas 

 projecting from the lowest part, so that the carbon dioxide, which is heavier than air, could be 

 completely removed. The inlet for purified air was just below the cover of the chamber. Inside 

 the chamber was a loose, false bottom, perforated with numerous small holes, which prevented 

 the cranberries from settling down and blocking the outlet. The false bottom supported a 

 tube three-eighths of an inch in diameter which rose through the center of the chamber and 

 projected an inch above the cover. This tube was also perforated with holes in the portion below 

 the cover, and served to hold a thermometer and to permit free circulation of air through the 

 mass of berries. The cover was sealed in place by means of putty around the inner walls and 

 the central tube, and a cork, through which passed the thermometer, stopped the tube. The 

 outer end of the inlet tube was joined to the purification apparatus which consisted of a U tube 

 containing dry soda lime, and a bulb tube containing a strong solution of sodium hydroxide. 

 The air bubbling through the solution was moistened before entering the chamber, while the 

 bubbles marked the movement of the air and served to indicate leaking joints. The outlet tube 

 connected with a train of four small flasks, each of which contained a measured amount of stan- 

 dard solution of barium hydroxide, by which all the carbon dioxide was absorbed and precipi- 

 tated as barium carbonate. A current of air was drawn through the entire apparatus by an 

 aspirator which was regulated so that the air in the respiration chamber would be renewed 

 about once in every hour. As a rule, each experiment was run six hours. Some were conducted 

 for longer periods, but six hours was most convenient and satisfactory. 



