THE CLARIFICATION OF FRUIT JUICES. 21 



filtration and then by pasteurization in the final containers. A few 

 preliminary experiments in the season of 1919 gave some encourage- 

 ment to this idea, which was fairly thoroughly tested in the autumn 

 of 1920. Several methods of handling the juices were employed. 

 These will be outlined and their advantages and disadvantages 

 indicated. 



TREATMENT WITH EARTH, FOLLOWED BY SEDIMENTATION, BEFORE FILTERING. 



In order to ascertain whether mixing with diatomaceous earth, 

 sedimentation, and decantation prior to filtration would be advan- 

 tageous, a quantity of juice was divided into three lots. One of these 

 was strained through cotton cloth, to remove fragments of pulp 

 as completely as possible, and was then thoroughly mixed with 

 the earth at the rate of 1 ounce of earth per gallon (6 pounds per 

 hundred gallons). The second portion received an equal quantity 

 of earth but was not previously strained to remove the pulp. The 

 third lot was neither strained nor mixed with earth. The three lots 

 were then placed in 5-gallon carboys, which were filled to the neck, 

 corked, and placed in a basement room at a temperature of 55° F. for 

 18 hours, to allow sedimentation to occur. At the end of this time 

 the lot which had received no treatment showed a fairly compact 

 precipitate about 2 inches thick at the bottom of a 5-gallon carboy ; 

 the other two lots showed compact deposits 3 to 3| inches thick, above 

 which was a zone of less closely aggregated material, followed by 

 poorly defined zones, each containing less suspended material than the 

 next below. In this respect the lot which had been strained through 

 cloth showed little, if any, difference from the unstrained lot. On 

 carefully siphoning off the liquid it was possible to draw off 4f 

 gallons from the untreated carboy without greatly disturbing the 

 sediment. Of the lots treated with earth, it was possible to draw 

 off only 4| gallons from the lot which had been strained prior to the 

 addition of earth, and 4|- gallons from that which had not been 

 strained, before the liquid flowing from the siphon became very 

 densely turbid from the drawing up of loosely aggregated material. 

 There was consequently twice as much sludge in the case of treated 

 juices, but it was of a very much less compact character. 



Each of the three lots of juice was next treated with earth at the 

 rate of 1 ounce per gallon, thoroughly stirred, and immediately 

 filtered through a disk of earth with suction, the sludge from each 

 lot being placed on the filter and drained as completely as possible 

 after the siphoned liquid had passed through. A fresh filter disk 

 was prepared for each lot, and uniform suction was employed 

 throughout. The filtrates were equally brilliant. The juice which 

 had not received a preliminary treatment with earth required about 



