42 Transactions. 



Art. VIII. — Technical Analyses of Goal, and Goal-testing . 



By A. M. Wright, M.S. A. (London), Fellow of the German 



Chemical Society (Berlin). 

 [Read before the Canterbury Philosophical Institute, 7th June, 1905.] 

 As the results, so far as the estimation of moisture, volatile 

 combustible matter, and fixed carbon are concerned, are only 

 comparative, to be of any value it is necessary that they be 

 obtained under exactly the same conditions. 



The methods used for the various determinations in the 

 coals analysed are as follows : — 



Moisture. — Weigh 2—5 grams of the pulverised sample 

 into a platinum crucible ; place the crucible uncovered in an 

 air bath having a temperature ranging from 105° C. to 110° C, 

 and heat at this temperature for exactly one hour ; cool, 

 weigh, and call the loss in weight " moisture." As coal when 

 dried at 100° C. loses in weight for a time, and then grows 

 heavier, the sample cannot be dried in the ordinary way until 

 a constant weight is obtained. 



Volatile Combustible Matter. — Weigh 1-2 grams of the 

 sample into a platinum crucible, place the cover on tightly, 

 and heat over a good Bunsen burner for exactly three and a 

 half minutes ; then bring a blast lamp under the crucible for 

 exactly three and a half minutes more, taking care not to allow 

 the crucible and contents to cool while changing burners. 

 Cool and weigh, the loss in weight being moisture and volatile 

 combustible matter. This determination should always be 

 made on a fresh sample of coal, and not on the sample used 

 for the moisture-determination. 



Fixed Carbon and Ask. — After weighing the crucible for 

 the previous determination, heat over a good Bunsen burner 

 until the carbon is completely burned off and the residue 

 shows no unburned carbon. Cool and weigh ; the difference 

 between this weight and the last is the weight of fixed carbon 

 in the coal, and the residue in the crucible is the ash. The 

 sum of percentages of fixed carbon and ash is approximately 

 the percentage of coke that may be obtained from the coal. 



Sulphur. — Eschka's method was used, heating with an 

 alcohol-lamp. As this method is well known, no description 

 is needed. 



Heating -value. — For the actual calorimetric determina- 

 tions, Bosenhaim's modification of the Thompson calorimeter 

 was used ; for comparison, the calculated heating-values are 

 according to a formula suggested by the American Coal 

 Analyses Committee.* 



* Gbeui. News, 1898, p. 75 ; Trans. N.Z. Inst., vol. xxxi, p. 5(54. 



