COOLIITG HOT-BOTTLED PASTEURIZED MILK. 13 



only about 5° F. (2.8° C). Therefore, if the crates contaming pint 

 bottles were stacked on top of those containing the quarts, the tem- 

 perature thi'oughout the stack could be equalized to a certain extent. 

 This would reqmi'e, however, extra care and trouble in stacking. 



The curves in figure 8 are plotted from temperatures taken in quart 

 bottles in the first, third, fourth, and fifth tiers of crates, the bottles 

 selected having been immediately above one another and in line. 

 On account of not havmg a thermocouple available, the temperature 

 in the second tier was not taken. Curves 3, 4, 5, and 6 show the 

 difference m temperature of bottles in respect to one another when 

 placed one above the other. It will be noted that the difference in 

 temperature of adjacent bottles decreases rapidly as the distance from 

 the bottom increases and also that there is a wide difference in the 

 temperature of the top and bottom quarts. 



The curves 3, 4, 5, and 6, in figure 9, showing the drop in tempera- 

 ture of pmts and quarts, are nearer one another than those in figures 

 6" 7, and 8. This is owing to the initial temperature of the pint bot- 

 tles being about 13° F. (7.2° C.) lower than that of the quarts. It is 

 of course impracticable to adjust the initial temperatures of different- 

 sized bottles so that the cooling will be more nearly uniform through- 

 out the stack, and these curves are simply included as a matter of 

 general information. 



When the cold air is forced in at the bottom of the stack and up 

 through the crates, the variation in temperature in different-sized 

 bottles and the same-sized bottles at different positions in the stack 

 is too great for satisfactory operation, and we do not believe this 

 method would be commercially practicable. Consequently in our 

 next experiments the direction of the air through the stack was 

 reversed periodically, the cold air being blown through from the 

 bottom for 15 minutes and then through from the top for the same 

 period. 



BY FORCING THE AIR ALTERNATELY FROM BOTTOM AND TOP. 



The series of curves shown in figure 10 shows the effect of reversing 

 the direction of air through the stacks. The air was forced through 

 the stack from the bottom for 15 minutes, then reversed and forced 

 through from the top for the same length of time. This arrange- 

 ment was tried with the view of bringing the temperature of the top 

 and bottom bottles nearer together. It may be noticed that the 

 numbers on the curves in figure 10 do not correspond to those 

 in the previous figures. As before stated, these numbers refer to 

 the thermometers used in the work, and in the present case ther- 

 mometers 1 and 2 recorded the temperature of the incoming air — 

 one for the upward fiow, the other for the downward fiow. Nos. 

 8 and 9 recorded the outgoing air in a similar way. 



