22 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



beaker, where it is digested with 50 to 75 c.c. of water for 30 

 minutes ; filter, wash the residue twice with hot water by de- 

 cantation, then wash on the filter, small portions of water being' 

 .used for each washing, till the filtrate amounts to 200 c.c. 

 Bromine water is then added, the solution being made slightly 

 acid with hydrochloric acid. The amounts generally used are 

 4 c.c. of water saturated with bromine, and 3 c.c. of concen- 

 trated hydrochloric acid. Heat the solution to boiling till the 

 bromine is expelled, then precipitate the sulphur with 22 c.c. 

 of a hot 5 per cent, solution of barium chloride, which is slowly 

 udded from a pipette during constant stirring. The precipi- 

 tate is allowed to stand at a temperature a little below boiling 

 for two hours, or longer, before filtering. Test the filtrate 

 for acidity with litmus paper, and for excess of barium chlo- 

 ride with a drop or two of sulphuric acid added to a little in a 

 test tube. The preliminary washing of the precipitate is done 

 with hot water containing 1 c.c. hydrochloric acid per litre, 

 the final washing being made with hot water alone, and the 

 washing continued till it no longer reacts for chlorine when 

 tested with nitrate of silver. Ignite the filter paper and preci- 

 pitate in a porcelain crucible, using a low heat till the paper is 

 burnt oft' ; then raise the heat siifficiently to bring the precipi- 

 tate to a dull redness, and continue heating for a few mo- 

 ments, cool and weigh as barium sulphate. 

 Per cent. 



Ba 137 = 58.8 



S 32 = 13.7 



4 (54 27.5 



233 100.0 

 If one gram of coal was taken, then 



T, Weight of BaS0 4 ppt. wt. of filter ash x 13.7 



cent. = j-^v 



To determine the sulphur which remains in the coke, burn 

 2 grams of coke to an ash, heat the ash with 5 c.c. concen- 

 trated nitric acid and .about half a gram of chlorate of potash, 

 evaporate nearly to dryness. Add 15 c.c. concentrated hydro- 

 chloric acid and digest the solution for 15 minutes. Evaporate 

 1c< hard dryness. Moisten with 2 c.c. strong hydrochloric 

 acid, add 75 c.c. water and digest for 15 minutes. Filter off 

 the solution, wash with hot water and determine the sulphur 

 in the filtrate as sulphate of barium. The percentage of sul- 

 phur found in the ash deducted from the total sulphur in the 

 coal gives the percentage of hurtful sulphur emitted when the 

 coal is burnt. 



Phosphorus. It is only necessary to determine this sub- 

 stance in coke. Take 6.52 grains of coke and burn it to an 

 ash over a Bunsen burner or in a muffle furnace. Fuse the 



