AMERICAN BEET SUGAR. 39 



rising from it have a temperature of about 100 C., which passes over to the steam 

 chamber of the next body and causes it to boil ; the steam arising from it has a 

 temperature of about 88 degrees, which passes over to the steam chamber of the 

 third body causing it to boil ; the temperature of the steam arising and passing 

 over to the fourth body has a temperature of 76 degrees, which causes it to boil. 

 The difference in temperatures at which the liquid boils in each body is caused by 

 the difference in pressure, which is maintained by means of a condenser and 

 vacuum pump; the vapor arising from the last effect or body passes to a condenser 

 producing a vacuum in the last body of about 26", the liquid in the last effect 

 thereby boiling at a temperature of 60 C. The fourth acting as a condenser and 

 producing a vacuum to the third, the third for the second, and the second for the 

 first. 



The juice, flowing through the four effects, becomes more condensed as it 

 passes along, going in at a density of about 10, and coming out at 50, 

 which not only concentrates the sugar, but , the impurities ; this, which is techni- 

 cally called "thick liquor," is again submitted to the fumes of sulphurous acid, 

 which neutralizes it, destroys coloring matter, etc. The " thick liquor " is again 

 passed through mechanical filters that remove any solid foreign matters, after 

 which it is boiled in the vacuum strike pan where the sugar is crystallized. 



VACUUM PAN. The ''vacuum strike pan" is a closed cast-iron vessel, about 

 ii feet in diameter and 14 feet high, and holds 35 tons of "melada" (sugar 

 and molasses) when full. 



In the lower portion are situated a number of copper coils through which the 

 steam passes without coming in contact with the boiling mass ; the vapor arising 

 passes to the condenser ; a pump draws off the non-condensable vapors. During the 

 operation a vacuum is maintained in the apparatus, the mass boiling at a low 

 temperature, which prevents burning. The operation is as follows : 



Juice is admitted to the pan, and when about half full steam is turned on and 

 the contents evaporated till it is "just about to sugar" (as would be said in a 

 maple camp); at this moment fresh juice is admitted, and the whole mass thinned, 

 but not enough to dissolve the microscopic crystals ; it is again allowed to con- 

 centrate by evaporation, thickened, and the sugar in the freshly admitted juice 

 will join the microscopic crystals, which increasing in size will now be apparent to 

 the eye ; the mass is not allowed to concentrate enough to form more microscopic 

 crystals, but again thinned by adding fresh juice before that point arrives which 

 causes the crystals to grow in size without forming new ones ; this operation of 

 concentrating and diluting the mass goes on till the " strike pan " is full, the size 

 of the crystal and the hardness depending upon the way in which the operation 

 is conducted. It is at the will of the operator whether large, small, hard or soft 

 crystals are made ; by keeping the average of the boiling mass thin, the crystals 

 will be large ; thick, they will be fine ; hot, they will be hard ; cool, and they 

 will be soft. 



When the operation is complete, the whole mass (" magma ") is concentrated 

 till it contains about 75 per cent, sugar and 25 per cent, molasses (the latter being 

 7 to 10 per cent, water) in its composition. The steam is then shut off, air ad- 

 mitted, and a large valve at the bottom opened, the entire mass, weighing 35 tons, 

 allowed to run out as soon as possible before it has time to solidify. 



THE MIXER. The "magma" falls into a large iron tank, with revolving pro- 



