THE CLARIFICATION OF FRUIT JUICES. 11 



ture. Norris and McAllep {22) have published a note on the use of 

 diatomaceous earth as an aid to the filtration of small quantities of 

 raw cane juice in the laboratory, using brass wire screen beneath the 

 filter paper in a Buchner funneL Heriot {15, p. 205-206) describes 

 a method of employing kieselguhr on a factory scale in filtering 

 cane juice. Zerban {35), whose paper cites a number of papers from 

 the older literature on the use of kieselguhr, has reported the results 

 of both laboratory and factory scale tests of a specially prepared 

 diatomaceous earth, which was used in filtration of cane juice prepara- 

 tory to filtering through carbon, with excellent results. Wooster {33) 

 has patented a process of filtering raw cane juice which appears to be 

 essentially identical with those of Peck {25) and Zerban {35), since 

 it consists in the addition to the raw juice of kieselguhr and filtration 

 through filter presses. Martel {18) has designed a leaf filter which 

 is said to be highly effective in clarifying cane juice. The juice, as 

 it comes from the mill, is mixed with specially prepared diatomaceous 

 earth, agitated, heated nearly to boiling point, and forced into the 

 filters at low pressure — 30 pounds per square foot. Dale and Hud- 

 son {8) have described a process of clarification for use with sugar- 

 cane juice in sirup manufacture, the juice being heated to boiling, 

 mixed with diatomaceous earth at the rate of 5 to 6 pounds per 

 hundred gallons, and immediately pumped through a plate-and- 

 f rame filter press. With smaller quantities of the earth, filtration was 

 retarded by the formation of a slimy, almost impervious coating on 

 the filter cloths. The method gave a better clarification than it was 

 possible to obtain by the usual methods of straining and skimming, 

 and the resulting sirup was considered superior in flavor to the usual 

 commercial product. Coates {6) has reported satisfactory results 

 from the use of diatomaceous earth at the rate of 12 to 16 pounds per 

 ton in the filtration of tropical raw sugars in Louisiana sugar fac- 

 tories, the earth, previously made to a thin cream with water, being 

 added to the sugar prior to melting. 



Paine and Walton {23) have recently presented before the sugar 

 section of the American Chemical Society a report of a comparative 

 study of various diatomaceous earths with reference to their clarify- 

 ing efficiency for cane juices, finding that considerable differences in 

 physical properties do not materially affect the values of the various 

 earths for this purpose. 



Chace {5) has reported experiments upon grapefruit juices, in 

 which satisfactory clarification is obtained by pasteurizing the 

 freshly expressed juice, storing until sedimentation is completed, de- 

 canting, mixing with kieselguhr, filtering through cloth, bottling, 

 and pasteurizing. Cruess (7) mentions the fact that diatomaceous 

 earth may be used as an aid to the filtration of grape juices and 



