20 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



should a sample be incorrect it is misleading and valueless. 

 All coal seams are not equally good, even parts of the same 

 seam may vary in value, so it is quite possible to pick a sample 

 that will be much superior to what is mined on a large scale. 

 Analysis of samples taken years ago may not be representa- 

 tive of what is mined at the present day. The owners of a 

 mine that produces an inferor coal are not anxious to publish 

 the fact, though it soon becomes known in the trade; even 

 those who produce the better class of coal naturally prefer 

 to give prominence to their best results. Many published 

 comparisons of coals from different places are worthless, since 

 the samples we-re not taken under similar conditions. The 

 analysis of lump coal is nearly always better than the run-of- 

 mine from the same seam. 



Ultimate Analysis.* 



To determine the carbon and hydrogen, an Erlenmeyer s 

 combustion furnace is used, with 25 Bunsen burners. The 

 combustion takes place in a piece of combustion tubing, about 

 1m. long and 18mm. internal diameter: this allows the tube 

 to project about 10 c.m. at each end of the furnace, which 

 projecting portions are protected from the heat by a closely 

 fitting circular shield of asbestos. Air and oxygen are passed 

 through the tube over the sample, but so as to eliminate any 

 carbon dioxide or moisture it may contain, it first has to pass 

 through a purifying train. The purifying reagents are 

 arranged in the following order: sulphuric acid, potassium 

 hydroxide, soda-lime, and granular calcium chloride. The end 

 of the tube near where air and oxygen enter can be closed by 

 a rubbe'-r stopper, as there is no fear of volatile matter being 

 given off, since cool air passes through, but the other end is 

 closed with a closely-fitting, well-rolled cork. The rear, or cool 

 end of the tube, is empty for 25 c.m. inside the furnace, the 

 next 25 c.m. is filled with a loose layer of cupric oxide, with 

 u plug of acid- washed and ignited asbestos at either end, to 

 keep the wire-copper-oxide in place. After the copper oxide 

 comes 10 c.m. of coarse fused lead chromate, to retain any 

 sulphur products, this also being held in place by a plug of 

 asbestos. The absorption train consists of a six-inch Marchand 

 IT tube, filled with granular calcium chloride, to absorb water 

 formed by the oxidation of the hydrogen ; this is followed by 

 ordinary Liebig's bulbs, containing potassium hydroxide, to 

 which is attached a three-inch IT tube, containing soda lime 



*E. W. Parker, J. A. Holmes, and M. E. Campbell. Report 

 on the operation of the Coal Testing Plant of the United States 

 Geological Survey (Washington, 1906, published by author- 

 ity). 



