MOLASSES. 



Osmosis. It follows from the above sections that if the salts could be 

 removed from an exhausted molasses, the conditions of solubility of the sugar 

 would be altered and a further portion would be capable of crystallization. 

 About 1850 a method of effecting this was worked out by Dubrunfaut. The 

 principle of his process known as osmosis is as follows : If a concentrated solu- 

 tion of any soluble body be separated from a weaker solution or from water by 

 a semi-porous membrane, such as parchment, the two solutions will pass through 

 the membrane until they are of the same concentration. The rate at which 

 this osmosis or diffusion takes place is not the same for all bodies ; inorganic 

 salts such as potassium chloride diffuse much faster than sugar ; hence if a 

 solution of molasses be separated by a parchment membrane from water, a 

 greater proportion of salts will pass through the membrane in a given time than 

 sugar. An osmogene is an apparatus to effect this separation ; it consists of a 

 structure similar to a filter press in which are held a series of wooden frames, 

 shown in elevation in Fig. 217. Between each frame are placed sheets of 



Q/' 



0-"' 



FIG. 217. 



parchmentized paper, pierced at the angles to correspond with the apertures 

 shewn at A, B, C, D, and at A', B/, C', D', in Fig. 217. At b and c in the 

 one frame, and at a and d in the other, are small channels establishing commu- 

 nication with the interior of the frame. If, then, water enters at B and 

 molasses at D, the water will flow along the canal formed by the openings B 

 and into the interior of the frames by the channels b, and the molasses will 

 similarly flow by way of D and d'. The water will discharge itself along the 

 canal formed by the openings C and c, and the molasses along that formed by 

 the openings A l and a '. There is thus a continual flow of molasses and water 

 separated by a sheet of parchment. The water which leaves the apparatus 

 now charged with a proportion of molasses is called water of exosinose, and it 

 contains roughly about half the salts originally present in the molasses. 

 Although this process has been largely used in times past and is still to a 

 certain extent employed in beet sugar factories it is financially unsuccessful ; 

 the large size of the osmogenes required (500 square feet diffusion surface only 



397 



