3— STANDARDISATION OF COAL ANALYSIS. 

 By H. H. C. PuNTAN, F.C.S. 



I wish to put before you a plea for a uniform method or 

 standard for the sampling and analysis of coal, and have pleasure 

 in suggesting a working standard, which, if generally adopted, 

 would, in my opinion, greatly tend towards concordance of results. 



Sampling is usually done in a very haphazard manner at the 

 mines, and I feel sure that many conflicting analyses made by 

 different operators are more often due to defective sampling, than to 

 defective analysis. However accurately the analysis may be made, 

 if the sample is not representative, the result is worthless. 



I have now for some considerable time been using the method 

 adopted by the Committee of the American Chemical Society, and 

 with slight amendments in working details, find the method to give 

 wonderfully concordant results. The necessity for a standard method 

 of analysis is very obvious, when we consider, that the results we 

 obtain for moisture, volatile matter, and fixed carbon, depend wholly 

 upon personal equation, as the usual methods are more or less 

 conventional and arbitrary, with no agreement as to details, and 

 it is onlv by very strict attention to details, that work by different 

 operators will give concordant results. 



The working details for a standard method would be as follows : 



Preparation of Sample. — As soon as the coal is received, crush 

 it up and quarter down to about loo gram. Grind this up as fine 

 as possible in an ordinary coffee mill, and keep in stoppered bottle. 

 Grind about 15 grams of this to pass through a 60 sieve, and 

 also transfer to a stoppered bottle. 



Moisture. — Dry one gram of finely powdered coal in a platinum 

 dish in a w^ater bath for exactly one hour. For the Transvaal, I 

 would suggest, owing to higher elevation and lowering of boiling 

 point, that it should be dried in a bath of pure toluene, which boils 

 in Durban at io5°C., but would in the Transvaal approach the 

 temperature obtained by a water bath in Durban.* Cool and weigh 

 quickly. 



Volatile Combustible Matter. — Place i gram of finely 

 powdered coal in a weighed platinum crucible, with a fairly 

 light lid, upon a platinum or pipe-clay triangle, and apply 

 the full flame of a bunsen burner for exactly seven minutes. 

 I have found seven minutes for Natal coal to give the most 

 concordant results. The full flame of the burner should be 

 about 20 cm. high, and in use should be about 8 cm. above top of 

 burner. The upper surface of the lid should burn clear of carbon, 

 but the under surface should remain covered with carbon. Draughts 

 are to be avoided. 



Ash. — Burn the portion of coal used for moisture determination 

 at first over a very low flame, with crucible open and inclined, till 



* Pure toluene boils at ill" at sea level.— Ed. Ccmm. 



