ioo8 The Production of Beet Sugar, [march, 



and decompose the non-sugars, and to carry suspended 

 organic bodies down with it. This defecation may take place 

 in a separate vessel or in the carbonatation tank. 



Carbonatation is brought about by driving carbon dioxide 

 into the defecated or purified raw juice by means of pumps. 

 This causes the formation of calcium carbonate, etc., which 

 form a precipitate. After this first carbonatation, or saturation 

 of the juice with C0 2 , it is pumped up to the filter presses 

 which separate the suspended precipitate and the partly 

 purified juice. This treatment is repeated in a second car- 

 bonatation tank and filter press and sometimes a third, where 

 the alkalinity of the juice is finally adjusted. 



The residual lime-cake is conveyed by means of transporters 

 to a heap outside and eventually is given to the farmers or sold 

 for about 2s. to 3s. a ton. It contains : 



0-46 per cent. Potash (K 2 0). 



1-28 



, Phosphoric acid (P^Og). 



I '22 , 



, Magnesia. 





, Calcium carbonate. 



21*23 



Organic matter (fine beet rootlets, &c. ). 



50'00 , 



, Water. 



16-56 



Other constituents. 



IOO'OO 





The purified thin juice passes on to the evaporators (see Fig. 

 2) in order to evaporate some of the water (about 80 per cent, 

 of juice weight) and convert the thin juice from about 13 0 

 Brix., into a thick juice having a density of about 6o° Brix. 

 In order to effect this operation economically, the 

 evaporation system is based on the principle that the latent 

 heat is used over and over again, in modern factories generally 

 four or five times. The evaporating pans are arranged in 

 series, and the first vessel is heated either by direct steam, 

 exhaust steam, or high pressure vapour from a juice pre- 

 boiler ; the exhaust steam or vapour is condensed after parting 

 with its heat to the juice or liquor in the first vessel. 



The vapour which is given off from the juice thus heated, 

 now passes into the heating chamber of the second vessel, 

 where it in its turn is condensed and gives off its heat to the 

 juice in this vessel. The same process is repeated in the 

 third and fourth vessels. 



