90 THK KESPIRATIOX OF APl'LKS. 



just below the glass cover, and an outlet tube was tixed in 

 the bottom of the vessel which was shaped like a funnel, so 

 that the gas would all collect around the outlet, since car- 

 bonic acid is heavier than air. Air could be drawn into the 

 copper can through the inlet tube after first passing through 

 a bent glass tube containing a solution of caustic potash, 

 which removed any carbonic acid which was in the air. 

 It would then pass out through the outlet tube which was 

 connected with some glass bulbs containing caustic solu- 

 tions to collect all carbonic acid passing out of the can. 



The current of air through the apparatus was maintained 

 by connecting the absorption glass by means of rubber 

 tubing with a large jar of water, from which a small stream 

 was allowed to trickle at a rate that would keep the air 

 steadily bubbling through the potash solutions connected 

 with the inlet and outlet tubes. 



The copper vessel stood inside a galvanized iron tank 

 which could be filled with water or ice when low tempera- 

 tures were desired. The temperatures at which most of the 

 experiments were carried on were 32° Fahrenheit, or that 

 of modern cold storage rooms, 40° to 50° corresponding to 

 cool cellars and 68° to 80°, or room temperatures equivalent 

 to early fall. 



At the beginning of an experiment about two kilograms 

 (four to five pounds) of perfectly sound Baldwin apples 

 were placed in the copper chamber and the glass cover was 

 firmly sealed in place M^th putty. The current of air was 

 started through the apparatus and made to continue until it 

 was considered time to determine the amount of carbonic 

 acid which had been collected. The length of time which 

 had passed since starting the current was noted down and 

 the circulation was then stopped by shutting off the stream 

 of water. The potash solutions were next analyzed for 

 carbonic acid and finally the apples were removed from the 

 can until another experiment was begun. 



The length of time during which the carbonic acid was 

 collected ranged from 5 hours to 48 hours of continuous 

 circulation. In the earliest experiments it was found 

 inconvenient to keep up the circulation of air outside of lab- 

 oratory hours, and the runs were therefore made short in 

 order to make the necessary determinations of carbonic 

 acid at the end. Later, it was made possible to keep up a 

 continuous circulation over night and several long periods 

 of 24 to 48 hours were conducted at the different 

 temperatures. 



