52 MASS. EXPERIMENT STATION BULLETIN 355 



DEPARTMENT OF ENGINEERING 

 C. I. Gunness in Charge 



Cranberry Storage Investigation. (C. I. Gunness, H. J. Franklin, and C. R. 

 Fellers.) A fairly complete report on two years' work on the storage of cran- 

 berries was made in the 1937 annual report. It indicated that berries kept at 

 35° showed the smallest storage loss but that berries would color better at 45° 

 with only slightly greater loss than at 35°. 



The tests made during the 1938 season checked the results obtained in 1936 

 and 1937. Berries were held in refrigerated rooms at 35°, 45°, 55°, and 60° and 

 in one common storage. Berries were held at 55° and 60° in order to see whether a 

 difference of 5° in temperature would have any appreciable effect on storage loss. 

 The temperature of 60° is approximately that obtained in common storage. 

 Early Blacks showed a 2 percent greater storage loss when kept at 60° than when 

 kept at 55°, and Howes had a 5 percent greater loss at the higher temperature. 

 This indicates that many growers may be able to reduce losses in common storage 

 by making some effort to obtain lower temperatures in the storage. The first 

 and most obvious step is to provide good ventilation to cool the berries as they 

 come from the bog. The building of large, close stacks of warm berries within 

 the storage should be avoided. Good circulation of night air, either by natural 

 draft or by means of fans, is very desirable. In some cases it may be worth while 

 to insulate the storage to help hold the low temperature obtained during the 

 night. 



The 1936 and 1937 trials indicated that berries colored better at 45° and 50° 

 than at 35° or 40° or at the temperatures in common storages. In the 1938 trials 

 it was found that berries colored better at 45° than at 35° or at the higher tempera- 

 tures of 55° and 60°. In an effort to obtain good coloring with minimum storage 

 loss, one lot of berries was stored at 45° for a short period and then transferred 

 to 35°. The storage loss was slightly greater than when berries were stored 

 continuously at 35° and lower than when they were stored continuously at 45°, 

 and the development of color was almost as good as for berries kept continuously 

 at 45°. The practice of holding the storage at 45° during filling and for a period 

 thereafter gives promise of being good management in that it calls for less refrig- 

 eration capacity than if the storage is kept at 35° from the time the berries are 

 picked . 



Frost Protection on Cranberry Bogs. (C. I. Gunness.) An experimental plant 

 for studying frost protection was installed at the Cranberry Experiment Station 

 in the spring of 1938. It consists of an aeroplane propeller driven by an 8-cylin- 

 der automobile motor. The propeller is mounted on one side of the bog and draws 

 relatively warm air from the high land surrounding the bog and drive? it out over 

 the bog, displacing the cold air surrounding the vines. 



The purpose of the experiment is to determine the amount of temperature 

 inversion above the bog, the rise in temperature which can be produced on the 

 bog with a given temperature inversion, and the area which can be protected 

 with a single unit. 



Only two runs were made in the spring of 1938. The results obtained showed 

 promise for this form of protection, but insufficient work was done to warrant 

 any conclusions as to its effectiveness. The work will be continued next season. 



Tobacco Seed Cleaner. (C. I. Gunness.) A tobacco seed cleaner was made 

 in the spring of 1938 in cooperation with the State Seed Laboratory. This machine 

 operates on the principle that if tobacco seed is allowed to drop into a horizontal 

 blast of air, the light seed and chaff will be carried farther than the heavy seed. 



