74 



TiMEHRI. 



The present method is the addition of an alkali, gene- 

 rally a solution of caustic lime. This, coupled with heat, 

 coagulates the greater portion of the sap, which sub- 

 sides ; most of what remains, on the further application 

 of heat to boiling point, rises to the surface and is 

 removed in the shape of scum. 



The result, however, is by no means the desideratum, 

 a mixture of sugar and water ; it contains a large propor- 

 tion of glucose and also some soluble salts of lime. Right 

 through the subsequent operation of evaporation, these 

 salts are present, and it is to be presumed that they 

 continue to do a deadly work and convert crystallizable 

 into uncrystallizable sugar. 



Doubtless the "sugar do6lors" of the colony have 

 succeeded in largely increasing the recovery of the sugar. 

 This increase is chiefly due to the adoption of the 

 modern method of evaporation at low temperature in 

 vacuum. But the polariscope still shows an amount of 

 sugar largely in excess of what is obtained, even when 

 allowance is made for the deleterious aftion of the glucose 

 wbich is revealed by the " copper test." and the natural 

 salts found in the ash of the cane juice. 



The question is, therefore, whether all or at least a 

 great part of this separation could not be better effe6led 

 by eleftricity, which could not add a foreign substance 

 to the cane juice. Would not cane juice so defecated 

 be more nearly the desideratum, viz., a mixture of sugar 

 and water? 



The first experiment in this direftion, that I ever saw, 

 was made at Plantation Bel Air many years ago. 

 An attempt was made to filter cane juice through 

 granules of two metals, such as iron and zinc, which were 



