THE DETERMINATION OF CANE SUGAR 529 



Sulphuric Acid. Dissolve about five grms, in dilute hydrochloric acid ; 

 separate the silica as before, and in the hot filtrate precipitate the sulphuric 

 acid by barium chloride; allow to settle for six hours, filter, wash, dry, 

 ignite, and weigh as BaSO 4 : BaSO 4 X 0-3427 = SO 3 : BaSO 4 X 0-5828 

 = CaSO 4 . 



The analysis of the lime is performed exactly as for limestone ; very often 

 large quantities of alkalies are found in the lime, especially if the limestone 

 has been burnt with wood fuel in a short-flame kiln. In addition to the 

 chemical analysis of the lime, a mechanical bulk analysis for the determina- 

 tion of stones, unburnt limestone, etc., may be made ; very considerable 

 quantities of these materials are often found. The following are special 

 methods of lime analysis : 



Free Lime. Dissolve about one grm. of lime in a 25 to 30 per cent, 

 solution of sugar ; make up to definite volume, filter and titrate an aliquot 

 part of the filtrate with normal acid. 



Unburnt and Slaked Lime. Dissolve about one grm. of lime in a definite 

 quantity of normal acid and determine the excess of acid by titration with 

 normal alkali ; the difference between the total lime, as thus found, and the 

 free lime, as found above, gives the unburnt lime. 



Degener-Lunge Method. 100 Slake about one grm. of lime with water 

 and titrate with normal acid, using phenacetoline as indicator. The point 

 at which the indicator changes from yellow to red marks the neutralization 

 of the free lime ; the addition of acid being continued, the point at which the 

 unburnt and slaked lime is neutralized is marked by a change from red to 

 golden yellow. 



REFERENCES IN CHAPTER XXV. 



1. Int. Sug. Jour., 1907, 99, 481. 



2. Int. Sug. Jour., 1915, 17, 360. 



3. Int. Sug. Jour., 1914, 16, 112. 



4. Chem. News, 52, 280. 



5. Bull. Assoc. Chim. Sue., 1893, 10, 656. 



6. H.S.P.A. Ex. Sta., Agric. Ser., Bull. 32. 



7. " Handbook for Cane Sugar Manufacturers," New York, 1915. 



8. " Agricultural Analysis," New York, 1906. 



9. Ber., 1877, 10, 1043. 



10. Publicacion Laboratorio chimici dele Gabelle, Rome, 1891, 47. 



11. Z. fur Instr., 1896, 47. 



12. Ber., 1876, 9. 487, 1531 : 1884, 17, 2234. 



13. C.R., 107, 390. 



14. Ann. Chem., 232, 169. 



15. Jour. Prak. Chem. [2], 25, 114. 



16. Ber., 1880, 13, 1922. 



17. Ber., 1889, 22, 265. 



1 8. Jour. prak. Chem. [2], 22, 97. 



2N 



