348 MASS. EXPERIMENT STATION BULLETIN 260 



state during surplus periods for later use in ice cream. Cream of low 

 acidity will remain in good condition for several months if sufficiently 

 low temperatures are employed; i.e., 0°F. or lower. Ice cream of desir- 

 able flavor can be made from frozen sweet cream provided not more than 

 one-third of the fat content of the product is derived from this ingre- 

 dient. 



Ice cream mixes containing frozen sweet cream are high in viscosity, 

 due in part to excessive clustering of the fat globules after homogeniza- 

 tion. Frozen sweet cream has been found to be an overrun deterrent, 

 such mixes requiring about 10 to 20 per cent more time to whip. An 

 attempt is being made to find a method for storing sweet cream so that 

 it can be used without increasing the mix viscosity and length of freezing. 

 Data secured to date indicate that combining some of the gelatin or 

 sugar with the cream previous to freezing will produce a resultant mix 

 of lower viscosity and a more normal freezing time. 



A Study of Electric Refrigerated Milk Cooling Tanks. (J. H. Frand- 

 sen and H. G. Lindquist.) Work on this project was started in the 

 summer of 1929, the object being to determine the efficiency and cost 

 of cooling milk in electric refrigerated cooling tanks. Several different 

 makes of electric refrigerated units have been installed and data col- 

 lected as to the length of time required to cool milk from 90 to .50°F., 

 and the amount of current necessary to cool milk under ordinary farm 

 conditions. The data thus far collected are not sufficient to warrant 

 definite conclusions. 



A Study of the Ckanges that Occur in the Storage of Frozen Sweet 

 Cream. (H. G. Lindquist). Preliminary experiments have been made, I)ut 

 not enough work has been done to justify conclusions. 



DEPARTMENT OF ENTOMOLOGY 

 H. T. Fernald in Charge 



Dates of Hatching of Scale Insects and When to Spray for Them. 



(A. I. Bourne). The necessary observations on critical stages in seasonal 

 development of these insects and their correlation with climatic conditions 

 for the past season have been recorded. 



The scarcity of previous work along these lines gives almost no back- 

 ground of accumulated facts to assist in interpretation of results. This 

 has necessitated observations over a long period, to determine accurately 

 the influence of abnormal seasons. 



It has been found that the variations in temperature in late fall and 

 the severity of the following winter exert a great influence upon the rate 

 of development of these insects. 



The marked contrast in weather conditions in the years 1928 and 1929 

 has afforded unusual opportunity to determine the effect of such extremes, 

 particularly upon the spring appearance of young scales in the single- 

 brooded species. Oyster-shell Scale, and upon similar development in the 

 suiiinier generation of a two-brooded species, the Pine Leaf Scale. 



Investigation of Materials Which Promise Value in Insect Control. 

 CH. T. Fernald and A. 1. Bourne). Tlie chief attention this season has 



