6 
BULLETIN 895, IT. S. DEPARTMENT OF AGRICULTURE. 
cooling to the freezing point, but it is thought not to take more than 
fifty seconds. It was found usually that if not undercooled too 
rapidly the potato sections would undercool to from 23° to 17.6° F. 
before self-inoculation took place. 
INOCULATION. 
The term inoculation has been used in this bulletin to mean the act 
of terminating by some mechanical means the undercooling process 
J/ 
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Fig. 1.— Diagram showing the undercooling and freezing points of two potatoes. One tuber (repre- 
sented by the solid line) was subjected to an air temperature of 15.S" F. The other tuber (repre- 
sented by the broken line) was subjected to an air temperature of 8.7° F. 
shortly after the freezing point has been passed. It is considered 
that this term is rightly used, as it is directly comparable to the 
process in physical chemistry, known by the same term, in which 
crystallization is started in a concentrated solution by adding a 
crystal of the solute or when freezing is started by adding a crystal 
of ice to pure water that has been undercooled. 
All materials are not so easily inoculated as sections of the potato. 
While determining the freezing point of cranberries it was found 
necessary to undercool them to a degree considerably lower than 
