BUREAU OF ANIMAL, INDUSTRY. 215 



weather than tlie use of either chlorin solution or salt and chlorin 

 solution. 



The length of life of teat-cup rubbers under heat sterilization 

 varied from 51 to 95 days. Investigations of teat-cup rubbers made 

 by the Bureau of Standards from material furnished by the Dairy 

 Division led to the conclusions that such rubbers should be properly 

 cleaned before sterilization, as any butterf at remaining on them has 

 a deleterious effect at the sterilization temperature, and that in order 

 to render good service the rubbers should be made from a so-called 

 " pure gum " compound. 



OTHER ACTIVITIES. 



A test for determining the holding time of continuous-flow pas- 

 teurizers was devised. Tests were m^de at commercial plants in 

 several localities. Experimental tanks in the department labora- 

 tories were also used to study flows and to check up the field experi- 

 ments. The results obtained are of great importance to machinery 

 manufacturers, milk dealers, and health officials. 



A galvanized-iron box steam sterilizer for dairy utensils was set 

 up and operated to obtain data on its economy and efficiency. A 

 temperature of 99.4° C. was reached in 35.7 minutes and maintained 

 for 12.7 minutes with 14.7 pounds of corncobs for fuel. The average 

 bacteria count of the interior surfaces of 10-gallon milk cans was 

 reduced from 48.366,666 to 1,667. Tests were made with steamed- 

 and unsteamed cans held covered for 24 and 48 hours in warm, 

 weather. Unsteamed cans having a bacteria count of 154,000,000: 

 contained more than 18,000,000,000 at the end of 24 hours, while 

 steamed cans having a count of 3,400 immediately after steaming and! 

 left practically dry had only 7,900 in the same time. The bacteria., 

 count on steamed cans left damp for 48 hours increased from 4,400 

 to nearly 6,000,000. 



Experiments concerning the effect of feeds on flavor and odor of 

 milk were continued. The work with green alfalfa, green corn, and 

 turnips has been completed and the results prepared for publication. 

 The conclusions are, in the main, similar to those reached with the 

 feeding of silage as reported in Department Bulletin 1097. 



Other subjects under study are the riilationship between the bac- 

 teria count of whole milk and that of the cream and skim milk 

 resulting from its separation, the factors affecting the foaming of 

 milk and cream, and factors affecting the viscosity of cream. From 

 data so far obtained it is apparent that the viscosity of cream is in- 

 creased as the temperature is lowered and the fat percentage in- 

 creased, and that it is lessened by holding the cream at a high tem- 

 perature and then chilling it. 



DAIRY RESEARCH LABORATORIES. 



The work of the daily research laboratories is of a technical char- 

 acter and much of it is unsuitable for detailed description in a report 

 of this kind. It has a practical bearing, however, on the solution 

 of many dairy problems and adds to the store of knowledge of dairy 

 science. Eesults are published from time to time in department 

 bulletins and technical journals. 



78007— AGE 1923 1 5 



