CHAPTER XXII. 
THE ACTION OF HEAT. 
The Influence of Heat upon Cane Juice—Imperfect convection of 
Heat in deep masses of Syrup—How Heat is economized by this 
Method, and its Intensity regulated, according to the Effect re- 
quired at each Stage of the Evaporation—The Tilt Pan—Injuri- 
ous Effects of a Low but Prolonged Heat—Soubeiran’s Experi- 
ments-—Open-air boiling indispensable up to a certain point of 
Concentration—Payen’s Experience—Evaporation by a Water- 
Bath or by Steam at 212° F.—Why injurious—Advantages de- 
rived from the use of a Vacuum Finishing Pan—Why it cannot 
come into general use. 
THE application of heat to cane juice until its tempera- 
ture rises to the boiling point, is capable, unassisted by 
other agents, of effecting an imperfect clarification. This 
it does chiefly by effecting the coagulation of that portion 
of the albumen of the juice not held in solution by the acid, 
and by the separation along with this albumen of a great 
part of the leaf green (chlorophyll) and other substances 
mechanically suspended in the liquid. 
During the subsequent evaporation the temperature con- 
stantly rises, and when it reaches a certain point the heat 
causes the decomposition of some of the nitrogenous impu- 
rities not before separated. This action of the heat, how- 
ever, may be very much assisted by the chemical action of 
lime. At a much higher temperature the sugar itself is 
decomposed (burnt), and the application of a very strong 
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