THE DEFECATION OF CANE JUICE 279 



sugar liquor of 60° Brix defecated with lime and phosphoric acid. It consists 

 {Fig. 164) of an aerating vessel, air at 15 lbs. gauge entering by the perforated 

 pipe d. The aerated material then passes by the pipe 6 into the separating 

 tank pro\'ided with steam coils and vertical baffle plates. The precipitate, 

 to which the air bubbles have attached themselves, rises to the surface and 

 continually passes off into the gutter 8, its motion being aided by two hori- 

 zontal rollers not shown in the drawing. The clear liquor is also continuously 

 removed by the pipe 7. After long 

 intervals particles which escape aera- 

 tion and deposit on the bottom are 

 removed. At the time of writing, 

 the author is unaware of the adaptation 

 of this apparatus to juices. 



Although only indirectlj' connected 

 with defecation, the Thomas-Petree 

 process can be referred to here. As 

 described for a three-mill combination 

 in U.S. patent 1,266,882 the juice from 

 the first mill is treated separately, the 

 defecation mud there obtained being 

 mixed with diluter juice coming from 

 the second mill. A second defecation 

 obtains here, the clear juice joining the 

 first mill juice prior to defecation and 

 the mud being pumped over the ba- 

 gasse on its way to the second miU. 



Imbibition water is applied before the third unit, and the juice here ex- 

 pressed forms as usual the diluting agency for the imbibition at the setond 

 mill. This process, which ehrninates the filter-press station, is at the time of 

 writing in extensive use in Australia. 



Centrifugal Separation. — Bessemer's patent (13202, 1850) contains the 

 first notice of this means. He proposed to filter the juice through flannel 

 in a centrifugal, and also aimed at making the process continuous by re- 

 moving the matter intercepted by the flannel by scrapers moving a little 

 faster than the basket. Possoz' patent (1859 of 1861) introduces the 

 double carbonation process, and includes the separation of the lime sludge 

 in an imperforate centrifugal with continuous discharge of the clear effluent 

 over the lip. This same means is found in the later patents of Laidlaw 

 (1188 of 1897), of Herriot (29286 of 1897), of Hignette (28589 of 1897), of 

 Kopke (29640 of 1913) and in various others. All these adhere closely to 

 the sugar dr5dng type, and none have come into general use. 



Fig. 164 



REFERENCES IN CHAPTER XIV. 



Trails. Cambridge Philosophical Soc, 1855, 9, 8. 

 Trans. Amer. Inst. Min. Eng., 1916, 55, 336. 



