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MANUFACTURE OF SUGAR. 



but of these, the two most efficacious are dangerous from 

 poisonous ingredients being used, and would therefore 

 be improper to be intrusted to careless persons. There 

 are also several patented processes, but their success is 

 as yet undetermined, and they are open to similar objec- 

 tions. The niters generally employed and recommended 

 are Taylor's bag filters, which have long been used in the 

 refineries in this country; but a much more simple and 

 equally effective method is used by the French, both 

 in the beet-root sugar factories, and also in the sugar 

 colonies. It is thus described by Dumas : — "In a large 

 box are placed vertically a score of flat cotton sacks, kept 

 distended by a slight wicker frame/'" (a spiral copper wire 

 would answer this purpose and be more easily kept clean,) 

 " the liquor to be filtered is poured at once into the open 

 space between and around the sacks, so that filtration, con- 

 trary to what happens in Taylor's system, takes place from 

 without. The filtered liquor flows into the double bottom 

 of the box, through a hole in the bottom of each sack. 

 The advantages of this plan are apparent, for as no deposit 

 can be made on the inside of the sacks, they will not 

 require such frequent cleansing; and for the same reason 

 * the filtration is more rapid, and the washing of the sacks 

 accelerated." Of the apparatus for filtration through 

 animal charcoal, Dumont's and Peyron's are most com- 

 monly used. The first is well described by Dr. Mitchell : 

 — " They consist of a range of boxes, varying in size and 

 number with the daily quantity of sugar required. They 



