CANE SUGAR. 



is a column c, provided with trays packed with chalk, serving to filter the gas 

 and to retain sulphuric acid. The upper surface of the oven is made double, 

 so that cold water circulation may cause the condensation of sulphur volatilized. 

 The sulphur dioxide passes along the pipe /, whence it reaches the bottom of 

 the sulphitation tanks, being evenly distributed by means of a perforated coil. 

 The ovens a are provided with doors, through which the sulphur is introduced, 

 contained in a basket. So as to be continuous in action, the ovens are worked 

 alternately. 



Another method, and one which in the writer's opinion is reliable and 

 easy of control, is shown in Fig. 1^.6. 



The sulphur is burned in the iron pot a, being introduced therein, in 

 quantities of about one pound at a time, through the aperture J, which may 

 be kept closed by a tight fitting movable lid. The air necessary for combus- 

 tion passes through the pipe c, which is filled with lumps of quicklime, which 

 are renewed daily. The draught and pressure necessary to force the sulphur 

 gas into the juice are obtained by the injector shown at e, working at not less 



FIG. 145. 



than 60 Ibs. pressure per square inch ; parts of this exposed to the action of 

 the gas are made of a lead-antimony alloy containing about five per cent, of 

 antimony. 



The use of sulphur is very old ; it was originally used by Melsens, in 1810, 

 and there is probably no subject connected with the sugar industry about 

 which so much has been written, and about which so little is actually known. 

 What is claimed to occur may be briefly summarized. 



1 . Juices are easier to filter. 



2. Masse cuites ' work better ' in the pan, and are easier to purge, owing 

 to a decrease in viscosity. 



3. A greater precipitation of impurities occurs. 



4. Juices are bleached. 



In so far as regards the bleaching action of sulphurous acid, it may be 

 remarked that any acid gives a light coloured juice ; Maxwell 6 , however, has 

 shown that sugar solutions coloured artificially by prolonged heating with acids 

 are completely decolourized by sulphurous acid. 



248 



