EXPEEIMENTS OF 1910. 



27 



might be successfully conducted by keeping the persimmons in air- 

 tight containers and relying on the fruit itself to exhaust the oxygen 

 of the air instead of replacing the air by carbon dioxid. 



The rate of respiration of the several varieties was first determined, 

 using persimmons just received from Florida by express. The fruit 

 was kept in desiccators in an automatically regulated constant tem- 

 perature chamber at 20.8° C. The method of conducting the measure- 

 ment is that described in Chemistry Bulletin No. 142, " Studies on 

 Fruit Respiration." The carbon dioxid evolved by the several varie- 

 ties is expressed in the table below in terms of milligrams per kilo- 

 gram per hour and in terms of the volume of carbon dioxid evolved 

 per kilogram of fruit during 24 hours. 



Rate of respiration of the several varieties of persimmons used. 



Varieties. 



Number 

 ol speci- 

 mens. 



Weight 

 in grams. 



Interval 

 in hours. 



Carbon dioxid evolved. 



Grams. 



Milli- 

 grams per 

 kilogram 

 per hour. 



Cubic 

 centi- 

 meters 

 per hour. 



Cubic 

 centime- 

 ters per 

 24 hours. 



Hachiya. . . 

 Tane-nashi 

 Triumph . . 



Tsuru 



Zengi 



2,130 

 2,276 

 1, 752 

 2,571 



2,484 



17f 

 171 

 17| 

 17| 

 171 



0. 8404 



.9636 



.5324 



1. 0430 



1. 1090 



22.3 

 24.0 

 17.2 

 23.0 

 25.3 



12. 22 

 13.15 

 9.43 

 12.61 

 13.87 



293.3 

 315.6 

 226.3 

 302.7 

 332.9 



As the varieties studied evolved from 226 to 333 cc of carbon 

 dioxid per kilogram in 24 hours, or roughly from one-fourth to one- 

 third of their volume, it could reasonably be expected that self- 

 asphyxiation would be successful, as if the air spaces between the 

 fruits in the container equaled the volume of the fruits, the oxygen 

 in the air inclosed would be well exhausted at the end of 24 hours. 



In the asphyxiation experiments which were begun on November 

 9, using the same varieties of persimmons from the same shipment as 

 those in the preceding respiration test, the fruits were shut up tightly 

 in 10-inch tubulated desiccators. These were fitted with delivery 

 tubes reaching to the top and bottom, respectively, so that samples of 

 the gases for analysis could be withdrawn at the conclusion of the 

 experiment before opening. Four desiccators were employed. One 

 contained the fruit only, another contained the fruit and 400 grams of 

 oven-dried starch, a third was filled with fruit and dry, clean sand, 

 which was poured around the persimmons so as to diminish consider- 

 ably the volume of the air spaces. In the fourth desiccator the air 

 was displaced by carbon dioxid. 



The desiccators were securely closed. Vaseline was used as a 

 lubricant between the ground-glass surfaces. The stoppers and 

 covers were kept tight by tying. The tube leading to the bottom of 

 each desiccator was capped with a rubber tube carrying a glass plug. 



