Standardisation of Coal Analysis. 55 



free from carbon. Examine ash for carbon, by moistening with 

 alcohol, and re-heating if necessary. 



Total Sulfhur. — Determine by Eschka's method as follows : — 



Weigh out I gram of finely powdered coal into a platinum dish 

 of 70 to 100 cc. capacity, and add 1.5 gram of an intimate mixture 

 of I part dry sodium carbonate and 2 parts light magnesium oxide. 



Mix the coal with this mixture intimately, using a platinum 

 spatula, and heat at first very cautiously, raising the temperature 

 very gradually. When the strong glowing has ceased, increase 

 the heat until in about 15 minutes the bottom of the dish is at a low 

 red heat. During the latter part of the operation, stir occasionally 

 with spatula. When all the carbon is burned off, cool and transfer the 

 residue to a beaker. Rinse out the dish into a beaker with 50 cc. water 

 and 15 cc. of saturated bromine water, and boil for 5 minutes. Treat 

 the insoluble residue twice with 30 cc. of water, boiling each time, and 

 finally transfer residue to filter, and wash until only a uunt 

 opalescence is given with nitric acid and silver nitrate. 



Add to this filtrate, which should have a volume of about 200 cc, 

 1.5 cc. of hydrochloric acid, and boil until bromine is expelled. Now 

 add to the boiling solution 10 cc. of a 10% solution of barium chloride. 

 This should be added drop by drop, especially at first ; with constant 

 stirring, allow to stand upon a hot plate, when it will soon get 

 perfectlv clear. Then filter off barium sulphate, and wash with hot 

 water until free from chlorides. Transfer the filter, and moist 

 precipitate to the lid of a platinum crucible, and heat with a low 

 flame, until the paper is burned. Finally heat to redness, cool in 

 dessicator, and weigh. A blank determination should always be 

 made, using all the reagents in the same quantities, and carrying 

 out the entire process in exactly the same manner as with the coal. 



Calori-fic Power. — The Lewis Thompson Calorimeter has the 

 advantage of simplicity, but the results obtained even from the 

 same coal are often erratic, and frequent trouble is causd by uncon- 

 sumed carbon. Still it has the great advantage of simplicity of 

 manipulation. 



While admitting the much greater accuracy of the bomb 

 calorimeters using compressed oxygen, I fear their use here would 

 be too expensive for a technical use. A united opinion, as to the 

 most suitable calorimeter to be used and to the type of coal used 

 for standardisation, would be desirable. 



In the discussion on the paper, Mr. J. Roberts said : — 

 It seems to me to be highly desirable that coal testing should be 

 put on a better basis than it is at present. As a user of coal, I have 

 found that published analyses of the same coal showed great 

 discrepancies : especially in regard to the quantity of volatile matter, 

 there seemed to be great uncertainty, and the amount of volatile 

 matter is most important to any coal consumer who studied boiler 

 economy ; a coal higher in volatile matter requiring different methods 



