304 SORGHUM. 



duction into the syrup of the soluble salts of potash or soda, and their 

 use is not to be advised under any circumstances, unless solely by way 

 of experiment. They are nearly all based upon the principle of Howard's 

 Finings, for which they are a very poor substitute. 



The use of sulphate of alumina for the removal of the potash pres- 

 ent in the juices is, however, a most important matter, and is largely 

 used in beet sugar manufactories and the refining of raw sugars, the 

 potash being crystallized out as alum. 



Lime- Sucrate Defecation. 



In 1865, Boivin and Loiseau, of Paris, invented a process for the 

 refining of raw sugars and the defecation of juices, by a process which, 

 although complicated and requiring careful supervision, appears to 

 have given excellent results. It is known as the lime-sucrate process, 

 and the general procedure is as follows: 



The freshly expressed juice is received into a tank, where it is agitated 

 with cream of lime, the amount of which is equal to from 1 to 2 per 

 cent of the juice. In this form, the juice will remain unchanged, and 

 may be kept even for Aveeks, if desired. 



When thoroughly figitated, the limed juice is treated with carbonic 

 acid (obtained from the lime-kiln or coal furnace) in large tanks, which, 

 owing to the frothing up of the juice in tliis operation, are filled to 

 only one-fourth or one-fifth their capacity, and by means of revolving 

 stirrers, it is kept in agitation during this process. 



When the frothing ceases, the addition of carbonic acid is discontin- 

 ued, and a portion of the juice is now tested by boiling for a few min- 

 utes and filtering. If the filtrate is of a pale straw color, and the pre- 

 cipitate upon the filter is not too gelatinous, indicating that not enough 

 carbonic acid has been added, or too granular, showing that too much 

 has been added (in the latter case, the filtered juice would be of a 

 darker color), the operation is successful. 



The object aiuied at is to introduce sufficient carbonic acid to nearly 

 precipitate the lime present, and yet to leave enough in combination 

 with sugar in the form of sucrate of hydro carbonate of lime, that, in 

 the boiling of the juice, the flocculeut precipitate produced may carry 

 down the impurities of the juice. This, then, is the critical point of 

 the whole operation. When it is found that the lime remaining dis- 

 solved in the juice is the right amount, the juice is boiled rapidly for 

 a lew minutes, and a pricipitate is thrown down containing nearly all the 

 impurities of the juice. 



It is now filtered by means of filter presses, and the juice, which, 

 after filtering, should be of a light straw color, is again treated with 



