CANE SUGAR. 



quantity of acid required to neutralize the carbonates of lime and magnesia. 

 The lime is determined as usual and calculated to carbonate ; if the percent- 

 age of calcium carbonate be divided by five, the quotient will give the number 

 of c.c. of normal hydrochloric acid required to neutralize the calcium carbonate ; 

 the difference between that found above as necessary to neutralize the lime and 

 magnesia carbonates, and the calculated number of c.c. necessary for the lime 

 alone, gives the number of c.c. requisite to neutralize the magnesia carbonate ; 

 this number, multiplied by 4 2, gives the percentage of magnesia carbonate. 



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 EaS0 4 ; BaS0 4 X '3427 = S0 3 : BaS0 4 X '5828 = CaS0 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 determination 

 of stones, unburnt limestone, &c., maybe 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. 



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

 quantity of normal acid and determine the excess of acid by titiation 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. 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 are neutralized is marked by a change from red to golden 

 yellow. 



490 



