24 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



105 (leg. C. as possible; the usual range is from 103" deg. to 

 108deg. C. At the end of this time put a cover on the crucible 

 and place it to cool in a desiccator containing calcium chlo- 

 ride. Weigh rapidly without the cover: the difference 

 between this and the original weight is taken as moisture. 

 The amount of hygroscopic moisture absorbed by the dry fuel 

 in 24 hours should also be noted. 



Ash. The one gram of sample taken for the determina- 

 tion of moisture is heated in a tilted porcelain or platinum 

 crucible with the cover off , so that there can be a free access 

 of air, either over a Bunsen burner or in a muffle furnace ; first 

 at a low red heat, which is gradually raised as the carbon is 

 removed. It is better to use the moisture sample than the 

 coke from the determination of volatile hydrocarbons, as this 

 sample can be burnt so much quicker if properly handled. The 

 combustion may be hastened by stirring occasionally with a 

 platinum wire. Care must be taken not to allow fusion, for 

 fear the fused mass should include unburnt carbon. The ash 

 is allowed to cool in a desiccator and weighed. The process is 

 repeated till the weight is constant, the result being returned 

 in percentage. The colour and condition of the ash should be 

 noted. Ferruginous and calcareous ashes are fusible and 

 clinker 011 the fire bars : aluminous and siliceous ashes remain 

 pulverulent. Sometimes it is necessary to analyse an ash. 



Volatile Hydrocarbons. One gram of powdered coal is 

 placed in a 30 c.c. platinum crucible which is covered with a 

 well-fitting lid so as to keep the air out. The crucible is sup- 

 ported on a platinum or pipe-clay triangle, and exposed to the 

 full flame of a Bunsen burner for seven minutes. The distance 

 from the bottom of the crucible to top of the Bunsen burner 

 should be 17 c.m., the flame from the burner being 1C to 20 

 c.m. long. To prevent air currents from interfering, place a 

 cylindrical asbestos chimney 15 c.m. long and 7 c.m. in dia- 

 meter round the flame; by this means a uniform heat is 

 attained, and the lid of the crucible is heated to a visible red. 

 When cooled in a desiccator and weighed, the loss equals the 

 volatile hydrocarbon plus the moisture : the latter is deducted 

 and the result returned in per cent. 



Fixed Carbon. The residue left after driving off the 

 moisture and volatile hydrocarbons consists of the fixed carbon 

 and ash. The ash is a dilutant, and when deducted from the 

 combined weight of the two, gives the weight of fixed carbon, 

 which is expressed in per cent. 



Coke. All coals do not coke. The residue left bv free 

 burning coals after driving off the moisture and volatile hydro- 

 carbons is in much the same form as the powdered coal when 

 first placed in the crucible. A true coke, which consists of 

 fixed carbon and ash, loses its original shape and forms a com- 



