THE CARBONATION PROCESSES 281 



glucinic and saccharinic acids are formed. These bodies are unstable and 

 form dark-colom-ed basic salts, which are insoluble only in alkaline solution. 

 With a still continued rise in temperature a more profound decomposition 

 obtains, with the formation of acetic, formic, and carbonic acids, the dark- 

 coloured basic bodies being broken down to simpler colourless combinations. 

 As a result of these reactions several methods of operating have been devised. 



Single Carbonation. — The raw juice is received in tanks, and is at once 

 mixed with 7 to 10 per cent, of its volume of milk-of-lime at 20° Baume, 

 corresponding to 1-5 to 2-0 per cent, of dry lime on the weight of the juice. 



Fig. 165 



As described in the earlier Java publications, the temperature of reaction was 

 60° C, reduced later to 55° C, and now finally given as lying between 45° C. 

 and 55° C, and as near as possible to 50° C. At this temperature very little 

 destruction of reducing sugars takes place, and no darkening at all due to 

 the formation of basic salts. After the addition of lime, carbon dioxide is 

 pumped into the juice, causing the precipitation of the lime as carbonate. 

 At a certain stage of the process the juice becomes very viscous, due to the 

 formation of a complex body, hydro-sucro carbonate of Ume, C^^^z^iv 

 2CaO{OH)2, sCaCO^. At this stage the juice froths violently, due to the 

 very imperfect absorption of the gas. With continued gassing this complex 

 body is broken up, and eventually a product with an alkalinity of about 60 

 mgrms. CaO\ per Utre, corresponding to 0-02 c.c. normal per 100 c.c, is 



