14 BULLETIN 921, U. S. DEPARTMENT OF AGRICULTURE. 



USE OF VEGETABLE DECOLORIZING CARBONS IN CONNECTION 



WITH INFUSORIAL EARTH CLARIFICATION. 



Much interest is being taken at present in the use of decolorizing 

 carbons of high efficiency in the manufacture of sirup and sugar. 

 Those which have been produced up to the time of this writing are 

 expensive and for economy must be used over and over again and 

 then reclaimed when their decolorizing power begins to diminish 

 appreciably. Therefore, it is essential for efficiency and economy 

 that the juice or liquor which the carbon is used to decolorize should 

 be as clean as possible, that is, with no dregs, dirt, or slime to clog 

 up prematurely the pores of the carbon. Filtration of the juices 

 with the aid of infusorial earth leaves them in an ideal condition 

 for treatment by the decolorizing carbons. 



Preliminary experiments with these carbons showed that a fine 

 sirup could be produced by this method. The juice after being 

 filtered with infusorial earth was thoroughly mixed with an amount 

 of an active decolorizing carbon, figured as 1 per cent on the solids 

 in the juice. After it had been repumped through a plate and frame 

 filter press to remove the carbon, it was lighter in color and clearer 

 than the best grades of Louisiana sirup. Though much of its char- 

 acteristic so-called cane flavor was lost, that retained was very mild 

 and pleasing and should win favor in those regions where sweetness 

 rather than strongly marked flavors is the quality principally de- 

 sired. 



The end of the grinding season prevented more extensive experi- 

 ments and tests on this subject. 



INFUSORIAL EARTH CLARIFICATION FOR SUGAR MANUFACTURE. 



A preliminary clarification of the sugar-cane juice by filtration 

 of the whole juice with infusorial earth is a subject that should be 

 considered by those interested in the production of white sugars on 

 the plantations. Naturally, the cleaner the juice going to the effects 

 and pans the better the final quality of the sugar will be. 



In crushing and grinding the sugar cane a great deal of very finely 

 divided particles of bagasse and other material becomes incorporated 

 with the juice. By the ordinary process of sulphuring, liming, and 

 settling much of this finer material is left in the juice as a fine sus- 

 pension. This material must have some deleterious effect upon both 

 the yield and quality of the final sugar. The precipitate formed by 

 sulphuring and liming the juices settles rapidly and completely, so 



