17 



on, the current of slices being diverted to an empty cell as soon as one 

 is filled. When the first cell is filled with liquid it is allowed to flow 

 into cell No. 2, and through it into cells Nos. 3, 4, etc., as fast as they 

 are filled with beets, and closed. The liquid flows from cell to cell 

 through the system of piping referred to above, the current of water 

 continuously entering cell No. 1. This is continued until all but two 

 of the cells of the battery are filled. The manipulation is then varied 

 by drawing liquid from the cell last filled with slices and liquid, into 

 a measuring tank before the current of liquid is turned into the next 

 cell of fresh slices. This portion of hot water has passed through ten 

 or twelve portions of fresh beet slices, has approximately eight- tenths 

 the density of the juice originally contained in the beets, and is called 

 "diffusion juice." The sugar is extracted from the beets partially by 

 a process of displacement of the juice by hot water, but largely by 

 the process of diffusion, the sugar diffusing from the slices into the 

 liquid which surrounds them. The beet slices contained in the cell 

 which was first filled have now been washed with ten or twelve suc- 

 cessive portions of water, and contain less than one-half of 1 per 

 cent of sugar. This cell is therefore emptied in order to make room 

 for more fresh slices. The process is continuous. Each time a cell 

 is filled with fresh beet slices and juice, and a portion of diffusion 

 juice drawn off, the cell at the opposite end of the line contains 

 exhausted slices and is emptied. 



The cells of a "diffusion battery" are sometimes arranged in a 

 straight line and sometimes in a circle. The appearance and con- 

 struction of different forms of batteries are shown on pis. 23 to 26 of 

 the exhibit. 



PURIFICATION OF THE JUICE. 



The "diffusion juice" is submitted to an elaborate proess of puri- 

 fication before it is in a condition suitable for evaporation for the 

 recovery of the sugar contained in it. Lime and carbon dioxide (car- 

 bonic-acid gas) are the agents principally employed for this purpose. 

 They are both obtained from a lime kiln, which is kept continuously 

 in operation (pi. 27 of the exhibit). The kiln is charged with coke and 

 limestone at the top and the burnt lime is withdrawn at the bottom. 

 Carbon dioxide is formed in large quantities in the kiln, both by the 

 combustion of the coke and by the decomposition of the limestone. 

 It is withdrawn at the top of the kiln by means of pumps, and forced 

 through the juice contained in the " carbonatation tanks" (see pis. 27 

 and 29 of the exhibit). The process of purification includes five nitra- 

 tions and two successive treatments with lime and carbon dioxide. The 

 juice coming from the battery is passed through coarse filters for the 

 purpose of removing small fragments of beet pulp. It is then treated 

 with a large excess of lime (2 to 3 per cent of the weight of the beets 

 worked), and carbon dioxide is then forced through the hot juice until 



2731 No. 0301 2 



