18 HUMAN BIOLOGY 



Keep one bottle at the temperature of the laboratory, 

 labeling it bottle No. 1, and put another, bottle No. 2, 

 in the refrigerator. Pasteurize the other two bottles in 

 accordance with the following directions : 

 "Set the bottles into the tray. . . . The pot is then placed on 

 a wooden surface (table or floor) and filled to the three 

 supports (in the pot) with boiling water. Place the tray 



FIG. 8. Straus Pasteurizer. 



with the filled bottles into the pot, so that the bottom of 

 the tray rests on the three supports, and put cover on 

 quickly. After the bottles have been warmed up by the 

 steam for five minutes, remove the cover quickly, turn 

 the tray so that it drops into the water. The cover is 

 to be put on again immediately. This manipulation is 

 to be made very quickly, so that as little steam as pos- 

 sible can escape. Thus it remains for twenty-five 



