COOLING, STORING, AND SHIPPING MILK. 



25 



the city. The same precautions which prevent milk from becom- 

 ing warm during shipment in summer also prevent it from freezing 

 in the winter. 



In some refrigerator cars it is possible to keep milk at a low tem- 

 perature during shipment, but most of the milk is shipped in cars 

 that frequently are opened in transit to receive new supplies, and in 

 which the ice, if any is used, is placed on the top of the milk cans. 

 Much of the cooling effect is 

 lost when * f 

 opened. 



the 



cars are 



thus 



RESULTS 



OF EXPERIMENTAL SHIP- 

 MENTS. 



To determine the relative 

 efficiency of ordinary milk 

 cans compared with jacketed 

 and insulated cans in keeping 

 milk cold during long ship- 

 ments, three experiments were 

 conducted as follows: 



In the first experiment 4 of 

 the 10-gallon cans used in the 

 previous tests were employed, 

 No. 1 being insulated, No. 4 

 having a 1-inch felt jacket, No. 

 5 having a |-inch felt jacket, 

 and No. 6 being the ordinary 

 milk can. The cans were filled 

 with milk cooled to 44° F. and 

 were hauled in an open truck 

 a distance of 13 miles from 

 the farm to the railroad sta- 

 tion. The air temperature dur- 

 ing the 2^ hours' haul was 

 about 80° F. Upon arrival at 

 the station the cans were 

 shipped in an ordinary baggage car which was opened in transit to 

 receive and discharge baggage from Washington, D. C, to New 

 Orleans, La., a distance of 1,120 miles. 1 



The rise in the temperature of the milk and the temperature of the 

 surrounding air during transportation was obtained by means of 

 recording thermometers. Figure 19 shows the rise in temperature 

 of the milk in each of the several cans, together with the air tem- 

 perature during the trip. The milk in the ordinary can reached 60° F. 



to 



NO. I tNSULfiCTED 



NO. 2 §f '• 



NO <*- Ij-AGKETEU " 



NO £"-£ ** 



NOG- BARREL 



£/*/ER/K 



Gi£" ROOM TEMP. 



«to 



O JO 20 3& 



T/M£- HOUK-& 



Fig. 18. — Efficiency of various types of cans 

 for holding milk. Temperature near zero F. 



1 The shipment of milk was supervised by C. S. McBride, of the Dairy Division. 



