MANUAL FOR SUGAR GROWERS. 99 



the operation of tempering. Various acids act with 

 different degrees of rapidity. The mineral acids, as 

 a rule, effect the change in a very brief space of 

 time. The organic acids act much more slowly. 

 This change of cane sugar to glucose is known as 

 inversion, from the fact that cane sugar, when ex- 

 amined by polarized light, rotates the plane of po- 

 larization to the right, while invert sugar rotates it 

 to the left. The art of the sugar -manufacturer 

 consists in extracting the sugar from the juice with 

 as little inversion as possible, for to inversion is due 

 the production of molasses, with its consequent loss 

 of sugar and loss of money, molasses being of small 

 value. The chief agents causing inversion are 

 acids, heat, and certain ferments to be referred to 

 later. 



The simplest method of manufacture consists in 

 boiling down the clarified juice to a thick syrup in 

 iron pans over a fire, and pouring out the syrup into 

 shallow trays to crystallise. These iron pans are 

 nearly hemispherical and are arranged in a series 

 usually of four or five diminishing in size from 

 the large one, into which the juice from the clarifier 

 flows, to the small one in which the final concentra- 

 tion is completed. These pans are placed over a 

 continuous flue, the fire being under the small pan, 

 the object of this arrangement being to diminish as 

 much as possible the time of final concentration ; for 

 as the syrup becomes dense it boils at a very high 

 temperature, and therefore inversion proceeds with 

 great rapidity. 



This in effect is the common method of manufac- 



