CANE SUGAR. 



and the acid bisulphites of the formula MHS0 3 . These two forms react 

 differently with litmus and phenolphthalein, the most generally used indicators 

 in the sugar house. Soluble sulphites react neutral with phenolphthalein, but 

 alkaline with litmus ; hence when a sulphured juice reacts neutral to phenol- 

 phthalein the normal sulphite is present, and such a juice may give an alkaline 

 reaction with litmus ; when a juice reacts acid with litmus, then bisulphites 

 are present. A distinction beween the two classes of sulphites is that the 

 normal calcium sulphite is insoluble, the bisulphite being soluble ; if, then, a 

 juice is sulphured in such a way that bisulphites are present, these remain in 

 solution ; in the evaporator they become decomposed into S0 2 and the normal 

 sulphite ; the former on oxidation accounts for the presence of sulphuric acid 

 in calandria water, and the latter also oxidizing appears as a scale of calcium 

 sulphate on the tubes of the evaporators. 



Use of Phosphoric Acid. A third agent employed as a clarificant 

 in more or less general use is phosphoric acid appearing under various trade 

 names as ' Clariphos,' * Ehrmanite.' It is used to counteract the effects of an 

 over application of lime, and also as an actual precipitant of non-sugar. If a 

 solution of phosphoric acid be added to a limed juice, the first effect is to pro- 

 duce a precipitate of calcium phosphate ; if this precipitate be collected it 

 will be found to contain a notable percentage of organic matter ; if, however, 

 the addition of phosphoric acid be continued, a soluble superphosphate of lime 

 is formed, and the original precipitate redissolves. 



Oxalic Acid. This body has also been, and sometimes is, used in a 

 similar way, and the precipitate of calcium oxalate, which does not redissolve 

 on adding an excess of oxalic acid, also contains a notable quantity of organic 

 matter. 



Carbonate of Soda. An excess of lime salts has the property of 

 making the molasses very viscid, and in some factories it is the practice to 

 clarify with lime and soda, using the latter to neutralize the natural acidity of 

 the juice, and the lime to effect precipitation of the albumenoids. 



Other Agents Proposed for Clarification. Upwards of six 

 hundred agents and combinations of agents have been proposed for use in 

 clarification ; they fall into two main classes, those that aim at a discoloration 

 of the juices and those that are intended to remove non-sugars from the juices. 

 The removal of non-sugars is often attempted by the precipitation within the 

 solution of a bulky precipitate, such as of alumina, phosphate of lime. The 

 proposed agents may be classified thus : 



1. Sulphur compounds, including sulphurous acid, soluble sulphites and 

 bisulphites, including those of the alkalies, alkaline earths, aluminium andiron, 

 hydrosulphites of soda and of lime. 



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