59 



with the main shell outside of the tubes. There are in-take and discharge 

 pipes for the juice connected with the open spaces in front of the heads. 

 The juice is pumped in at one end of the heater, passes through the 

 copper tubes where the temperature is raised to about 99" C, and emerges 

 into the space at the opposite head from which it is taken to the settling 

 tanks. There are other forms of juice heaters more complicated than 

 this and particularly those with the superheater. This is a second heater 

 placed on top of the first and so fitted as to raise the temperature of the 

 juice above the boiling point. This superheated juice then flows back 

 through the space which would otherwise be occupied by steam in simpler 

 form and the heat it contains is absorbed by the cold juice just entering 

 the heater, after which it is pumped to the settling tanks in the usual 

 way. This combination is sometimes known as a superheater and an 

 absorber. 



Fig. 14. — Juice heater. (Victor.) 



From tlie heater the juice passes to the settling tanks for twenty or 

 thirty minutes. If juice heaters are not used the juice goes directly 

 from the liming tank to the settling tanks. The heavier sediment drops 

 to the bottom, the scums come to the top, and the clear juice is drawn 

 off from the center of each tank by means of a flexible pipe controlled by 

 a float. ^Tien the clear juice has been drawm off until the scum ap- 

 proaches the sediment in the bottom of the tank it is indicated by the 

 cloudy appearance of the juice which flows from the end of the pipe, 

 which is then closed. A separate outlet is then opened in the bottom of 

 the tank and the mud flows into a receiving tank near the filter press. 



Filter press. — A filter press, as shown in the accompanying illustration 

 consists of a series of iron plates and frames placed alternately on the 

 main frame of the machine. The plates are corrugated and gi'ooved or 

 checked so as to leave as little surface exposed m the outer plane as 



