MANUAL FOR SUGAR GROWERS. 107 



pan while tlie other dipped into mercury. If the 

 vacuum were perfect, the mercury would rise to the 

 same height as in the barometer, — about thirty 

 inches. During the ordinary working of the pan the 

 vacuum is about twenty-six to twenty-eight inches. 



If the formation of grain be allowed to take place 

 when only a small quantity of syrup is in the pan, 

 this is known as " graining low down." It is often 

 the custom not to allow grain to form until a con- 

 siderable quantity of concentrated syrup is in the 

 pan, and this method of working is known as " grain- 

 ing high up." By graining high there is some sav- 

 ing in time ; but as a rule, particularly with small 

 pans, the grain is not so large or so regular as when 

 the syrup is grained low down. To obtain large and 

 uniform crystals it is necessary to allow the grain to 

 form slowly, admitting thin syrup in small quanti- 

 ties, and allow the boiling to take place slowly and 

 steadily. 



It sometimes happens from bad manipulation 

 that the whole of the mass becomes cloudy from the 

 formation of minute crystals. This condition of 

 things, known as false grain, is to be guarded 

 against most carefully, as it leads to considerable 

 loss ; the masse cidte under these conditions will not 

 part with its molasses, and a sticky unsaleable pro- 

 duct results. If the appeararlce of false grain be 

 detected at once, the difficulty may be overcome 

 and the false grain destroyed by admitting a consid- 

 erable quantity of thin syrup into the pan and rais- 

 ing the temperature of the boiling syrup by wholly or 

 partially destroying the vacuum for a short period. 



