926 



SCIENCE 



[N. S. Vol. XXXIV. No. 887 



tannin being disregarded for the moment) do 

 so, but the change is accompanied by other 

 autolytic processes, in equal rates, which 

 cause the digestion of the middle lamella, 

 and, probably, conversion of sugars and of 

 aromatic substances. Carbon dioxide, how- 

 ever, is peculiar in that the loss of astrin- 

 gency is materially hastened while, relatively, 

 the remaining changes are held in abey- 

 ance, being, however, hastened as com- 

 pared with normal conditions. Herein 

 lies the secret of the Japanese process, 

 the source of the carbon dioxide being the 

 fruit itself, as a result of respiration. As 

 Gore (1910, 1911) showed, a pure atmos- 

 phere of carbon dioxide, making available 

 a larger amount, may be used. I have re- 

 peated his experiments with the goal of im- 

 mediate practicality in view, and have suc- 

 ceeded in perfectly processing two varieties of 

 Japanese persimmons (Taber 129 and Mya- 

 hume) in chum barrels on a scale sufficiently 

 large to demonstrate the feasibility and low 

 cost of the method for the grower or mer- 

 chant. The mechanical features of the 

 churn barrel (of the " Daisy " churn) permit 

 the easy packing of the fruit in suitable 

 material and the lid may be made sufficiently 

 tight to imprison the carbon dioxide for the 

 period necessary without recharging. The de- 

 tails of the method will appear in another 

 form later. But this is not all, nor the most 

 important feature of this work. I have 

 further demonstrated that, under increased 

 pressure of carhon dioxid, the processing is 

 hastened, so that, with a pressure of 15 pounds 

 the time required may be reduced from six to 

 seven days, the time required under normal 

 pressure, to less than two days. The definite- 

 ness of the experiment on this score leaves so 

 little to be desired that I venture to detail it. 

 Six dozen fruits, of the two varieties men- 

 tioned in nearly equal numbers, were intro- 

 duced into an autoclave (The Eclipse Steri- 

 lizer) at 4 P.M., November 16. No packing 

 was used, the fruits being placed side by side 

 on cardboard trays. The air in the autoclave 

 was first displaced, after which the pressure 

 was increased to 15 pounds. A somewhat 



sudden lowering of the pressure from 15 to 14 

 pounds was attributed to the penetration of 

 the gas into the fruit, and, at the expiration 

 of 20 minutes, the pressure was again raised 

 to 15 pounds. During the night, however, the 

 pressure fell to normal, and, after recharging, 

 the safety valve was found to leak. After ad- 

 justment the pressure remained close to 15 

 pounds. At 5 p.m. the same day, the pressure 

 was raised to 18 pounds, but it fell during the 

 night to 17 pounds, falling to 15 pounds by 

 2 P.M. The autoclave was then opened, and 

 the fruit tested. The fruits examined, in all 

 about three dozen, by various persons, were 

 found completely processed, save that, up to 

 date, one particularly hard and light-colored 

 fruit was found very slightly astringent. By 

 way of further practical test, a dish of the 

 fruit was served to a number of guests at my 

 home on the night of the same day, and they 

 all found the fruit very hard, sweet and de- 

 lightfully aromatic. 



Fruits of the same lot, but processed two 

 weeks previously, yielded to the treatment 

 under normal pressure in seven to eight days. 

 The control experiment, in which fruits of 

 the same lot were exposed to normal pressure 

 in a churn barrel, yielded in 8 to 10 days. 



It should not be overlooked that this sur- 

 prisingly short period of two days may be too 

 brief for fruit which has just been harvested, 

 and may vary also with the time at which the 

 harvesting takes place. In any event, how- 

 ever, as the control shows, the time involved 

 will be materially shortened with increase of 

 pressure in the amount already indicated. 



The above experience leads us to infer that, 

 if the initial pressure had been constantly 

 maintained, the completion of the process 

 might have been still further hastened, while 

 it is possible that still higher pressures may 

 be correspondingly more efficient. Setting 

 this aside, since there are a number of ques- 

 tions regarding color, degree of maturity and 

 the like, in their relations to the rate and 

 agents of processing which must be further 

 studied, there is no doubt that the method of 

 making use of supranormal pressures of car- 

 bon dioxid may be employed to an advantage 



