[ 386 ] 



liquid. The addition of slaked quick-lime for neutralizing 

 the juice before boiling, is of the highest importance, But 

 just sufficient lime should be added to neutralize the acid or 

 else the colour of the sugar produced will be too dark. 



589. Maltose is produced naturally in germinating bar- 

 ley. Germinating barley dried and digested with water at 

 about 60 C, parts with its malt-sugar which can be obtained 

 from the solution by boiling it down. 



590. The difference of action of polarized light on differ- 

 ent kinds of sugar is a principle utilized in factories for testing 

 the purity of sugar or sugar-cane juice, with the help of an 

 instrument called polariscope. It consists of two prisms of 

 transparent calcite (Iceland spar) enclosed in a tube, between 

 which the saccharine solution is introduced. Light passing 

 through the outer prism, the saccharine solution and the inner 

 prism, traverses a layer of transparent quartz so adjusted 

 that the rotation caused by the sugar-solution can be detect- 

 ed and measured. The rotatory power of cane-sugar is 73*8 

 to the right and it may be found out by observing a 

 column of saccharine solution i decimetre in depth contain- 

 ing i gramme of pure cane-sugar in every cubic centimeter 

 of fluid. To get the rotation of any sample from this observ- 

 ed rotation divide the former by the depth of the column of 

 fluid multiplied by the weight of the sugar in each -cubic 

 centimetre of liquid. Thus, if a solution of 0*25 gram 

 of sugar in each C. C. of fluid has an observed rotation of 

 25 in a column 2 decimetres in depth, the rotatory power 



of the sample is r = 50. The percentage of cane- 



2 X O 25 



sugar in the sample would thus be (73-8 : 50:: 100 : x) 



IOOX5OX 10 _ 



g - = 077. f no invert-sugar is present, the pro- 

 portion of sugar present in the juice or solution can be found 

 by multiplying the rotation of the solution as observed by 

 polarscope by 100 and dividing the product by 73*8. 



