34 







the battery, and is provided with an opening and a spout opposite each 

 cell of the battery. The openings are closed at pleasure by a slide. A 

 movable spout completes the connection with any cell which it is desired 

 to fill with chips. 



WHAT IS DIFFUSION ? 



The condition in which the sugars and other soluble substances exist 

 in the cane is that of solution in water. This sweetish liquid is con- 

 tained, like the juices of plants generally, in cells. The walls of these 

 cells are porous. It has long been known that if a solution of sugar in 

 water be placed in a porous or membranous sack and the sack placed 

 in water, an action called osmose takes place, whereby the water from 

 the outside and the sugar solution from the inside of the sack each pass 

 through until the liquids on the two sides of the membrane are equally 

 sweet. Other substances soluble in water behave similarly, but sugar 

 and other readily crystallizable substances pass through much more 

 readily than uncrystallizable or difficultly crystallizable bodies. To ap- 

 ply this property to the extraction of sugar the cane is first cut into fine 

 chips, as already described, and put into the diffusion cells, where water 

 is applied and the sugar is displaced. 



WHAT HAS TAKEN PLACE IN THE DIFFUSION CELLS. 



For the purpose of illustration, let us assume that when a cell has 

 been filled with chips just as much water is passed into the cell as there 

 was juice in the chips. The process of osmose or diffusion sets in, and 

 in a few minutes there is as much sugar in the liquid outside of the cane 

 cells as in the juice in these cane cells; i. e., the water and the juice 

 have divided the sugar, each taking half. Again, assume that as much 

 liquid can be drawn from one as there was water added. It is plain 

 that if the osmotic action is complete the liquid drawn off will be half 

 as sweet as cane juice. It has now reached fresh chips in two, and 

 again equalization takes place. Half of the sugar from one was brought 

 into two, so that it now contains 1J portions of sugar, dissolved in 2 

 portions of liquid, or the liquid has risen to f of the strength of cane 

 juice. This liquid having f strength passes to three, and we have in 

 three 1 J portions of liquid, or after the action has taken place the liquid 

 in three is J- strength. One portion of this liquid passes to four, and 

 we have 1J- portions of sugar in 2 portions of liquid, or the liquid be- 

 comes |f strength. One portion of this liquid passes to five, and we 

 have in five 1}| portions of sugar in 2 portions of liquid, or the liquid 

 is f I strength. It is now called juice, and is drawn off and subjected 

 to the processes of the subsequent operations of the factory. From this 

 time forward a cell is drawn for every one filled. 



