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 the cars are thus fea 
opened. FF | ete ile Ne 
RESULTS OF EXPERIMENTAL SHIP- aN ttt tt 
Ne 
Ne ora 
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 24 hours’ haul was 
about 80° F. Upon arrival at 
the station the cans were 
lied 
FARES 
NO. I INSULATED Sa 
NO. 2 
NO 4- { JACKETED o 
S-+ 
Us 
co) 
TEMPERATURE, DEGREES F. 
i) 
10 
YLAVERAGE ROOF TEMP. 
10 20 
TIME = es 
Fic. 18.—Efficiency of various types of cans 
for holding milk. Temperature near zero F. 
shipped 1 in an ordinary baggage car which was opened in transit to 
receive and discharge baggage from Washington, D. C., te New 
Orleans, La., a distance of 1,120 miles.t 
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 milkin the ordinary can reached 60° F. 
1The shipment of milk was supervised by C. S. McBride, of the Dairy Division. 
