228 PLANT AND ORGANIC CHEMISTRY 



The fluid from the diffusion cell is placed in tanks for de- 

 fecation with lime, which is added in the amount of 1.5 per 

 cent, for sorghum; l though .75 per cent, has been found 

 ample in the case of juice from the sugar-cane. 2 



Much of the albuminoid and non-sugar organic substances 

 are carried down, and the sugar forms a soluble lime sucrate. 

 Carbonic acid is then pumped in, and the lime is precipitated, 

 and with it further impurities. This process of single carbona- 

 tation was found to work better with sorghum juice than 

 double carbonatation. 3 



The contents of the tanks are then carried to filter presses, 

 and the clear juice recovered from the lime cake. This juice 

 is partially evaporated, and then whilst hot put through bone- 

 black filters. The final evaporation of juice is conducted in 

 vacuum pans and its crystallization ends the process. 



Among the difficulties to be overcome in this process is the 

 acidity of the chips in the diffusion cells. This will cause a 

 loss from inversion of the sucrose and a greatly diminished 

 yield of crystallizable sugar. The high temperature needed 

 for the diffusion will aid in bringing about a lil$.e result when 

 the canes are not in proper condition. 4 



Various means were tried to prevent this inversion. It is 

 probable that fine carbonate of lime, if sprinkled over the 

 chips before they enter the battery, may obviate the diffi- 

 culty. 5 



The addition of lime to the water tanks which supply the 

 diffusion cells was not favorable for the full extraction of the 

 sugar. Analysis showed 2 per cent, less of sugar in this juice. 

 The loss was probably induced by the coagulation of the 

 albumin of the cane cells. 8 



The addition of milk of lime and sulphurous acid 7 to the 

 juice has a preservative effect, and juice so treated may be 

 kept unchanged for months. 



Among the reasons advanced for the process of carbonatation 

 may be mentioned that it does away with skimming the juices. 



1 Bui. No. 14, Chem. Div. Dept. of Agr., p. 54. 2 Ibid., p. 54. 



3 Ibid., p. 25. * Ibid., p. 28. 6 Ibid., p. 32. 



6 Ibid., p. 20. 7 Bui. No. 3, pp. 96, 97. 



