300, 301] Analysis of Gas Lime 177 



estimate the total sulphur and the sulphur in the form of calcic 

 sulphate. The ' sulphite ' sulphur is less frequently estimated. 



300. Total Sulphur.— Weigh out 2 grams of the gas 

 lime; transfer to a 12-oz. conical flask; add 5 grams KC10 3 ; 

 place a funnel in the neck to prevent loss by spirting, and 

 pour in 50 c.c. pure HN0 3 . When the reaction moderates in 

 violence transfer to a water bath, and heat until CI ceases to 

 be evolved ; this will take about an hour. Transfer to a wide- 

 mouthed beaker, washing the flask thoroughly with hot water ; 

 add 20 c.c strong HC1, and evaporate to dryness. Heat for a 

 minute on the sand bath. Cool, and moisten with 2 c.c. strong 

 HC1. Add 100 c.c. H 2 0. Stir well, and allow to stand for 

 twenty minutes. This operation will oxidise all the sulphur to 

 sulphuric acid, so that it will all be in the form of CaS0 4 . 

 Filter, and wash the precipitate with warm dilute HC1 (1-20) 

 to dissolve any traces of CaS0 4 left behind. 



The next process is to remove the excess of lime, which 

 would interfere with the subsequent precipitation. Render the 

 solution just ammoniacal, and add ammonium carbonate solution 

 in excess. Allow to settle, and decant through a filter. Wash by 

 decantation with hot water. To the filtrate add HC1 cautiously 

 until effervescence ceases ; then expel the dissolved C0 2 by 

 heating for a short time on the water bath. Raise to a boil, 

 add boiling BaCl 2 solution, and proceed to the estimation of 

 BaS0 4 as described in paragraphs 28-31. The percentage of 

 sulphur must be calculated from the percentage of BaS0 4 . 



301. Sulphur as Calcic Sulphate.— Weigh out 2 grams, 

 dissolve in HC1, and separate the silicates as described in 

 paragraph 271. Next separate the lime, and determine the 

 S0 3 present exactly as described in the last paragraph. The 

 HC1 will expel all sulphites and sulphides as S0 2 and H 2 S 

 respectively, and only the sulphur originally in the state of 

 calcic sulphate will be precipitated as barium sulphate. 



N 



