EXTRACTION OF SUGAR. 177 



manufacture of sugar, by the too rapid decomposition of the 

 crude juice, in warm climates. 



It is to be poured in cold solution upon the cane, as it passes 

 through the mill, so as to insure its intimate mixture with the 

 expressed juice. Here it exerts its antiseptic property, and 

 also, by its great affinity for oxygen, intercepts the action of 

 that gas upon the constituent of the juice. Its influence does 

 not, however, stop here, for when the mixture is heated to 

 212°, the caseum, albumen, and analogous nitrogenous matters 

 separate as a coagulum, and the liquid becomes materially 

 blanched. Thus it acts also as a defecating and bleachinoj 

 agent. It likewise prevents the formation of any new coloring 

 matter by the action of air upon the pulp, insures a more 

 perfect crystallization without the necessity of haste, decreases 

 the amount of molasses, and yields nearly double the quantity 

 of sugar obtained by the old methods. 



The sulphurous acid, in exerting this beneficial influence, 

 absorbs oxygen and becomes sulphuric acid, and as this latter 

 would transform the cane into grape-sugar, the lime base is 

 necessary to neutralize and convert it into insoluble sulphate 

 of lime as fast as it is formed. 



The sulphurous taste adhering to the sugar may be removed 

 by crushing and exposing it to the air. A more efl'ectual way 

 is to refine it until its weight is decreased one-tenth. A very 

 white and pure sugar is thus obtained. 



It may be observed, in regard to the reason given for having 

 a salt of sulphurous acid, that, if the acid were oxidized^ we 

 would have, it is true, the insoluble sulphate of lime, but also 

 free sulphuric acid. According to LUdersdorff this free acid 

 is not injurious. 



The English patent for Melsen'^ process appears in the 

 Lond. Journ. xxxvi. 229. The accompanying propositions 

 and claims, for the use of baryta or oxide of lead, are objec- 

 tionable, for the reasons stated below. 



LudersdorflF's method, especially applicable to beet-sugar, is 

 based upon the fact, determined by experiment, that juice con- 

 tains two kinds of extraneous matters, of opposite chemical 



12 



