[stansfield-gilmore] carbonization OF LIGNITES 89 



weighed in a stoppered weighing bottle. The residue at the close of 

 an experiment was weighed as soon as cold to determine the loss in 

 weight, and the portion required for the calorimeter was weighed out 

 by difference as nearly as possible fifteen minutes after stopping the 

 heating. 



Calculations and Curves: — For each test the loss in volatile matter 

 was determined by subtracting the weight of the moisture in the 

 sample taken from the observed loss, the result being expressed as a 

 percentage of the equivalent weight of dry coal. This is referred 

 to as the percentage loss of weight (volatile matter) on a moisture- 

 free basis. It should be noted that water originally present in the 

 coal is not regarded as "volatile matter" in the technical use of that 

 phrase, although water produced by the decomposition of the coal 

 is included in the volatile matter. 



In diagram I the loss of volatile matter is shown plotted against 

 the temperature at which the experiment was carried out; a separate 

 curve being shown for each of the series of tests described below. 

 In a few cases the points given represent the average of two or more 

 results. Diagram I also shows the calorific value of the carbonized 

 residue from each test, these values being similarly plotted against 

 the temperature of carbonization. 



Diagram II shows the total heat value of the carbonized residue 

 expressed as a percentage of the total heat value of the corresponding 

 weight of the original sample, plotted against the temperature of 

 carbonization. This diagram may therefore be described as showing 

 the thermal efficiency of the process with respect to the residue. The 

 curves given are deduced from the rounded curves in diagram I. 



Diagram III shows the calorific value of the carbonized residue 

 plotted against the yield; the yields being shown as percentages of 

 both the original coal and the moisture-free coal. These curves are 

 also deduced from the rounded curves in diagram I. 



Table II shows the summarized results of all the tests. For ease 

 of comparison, the results given are taken from the rounded curves 

 in the diagrams at definite temperature intervals. 



All results have been calculated to a moisture-free basis as 

 described above. This gives a more stable basis for comparison, as 

 the moisture in the coal as received is liable to show considerable 

 variation. It is also a more satisfactory basis when it is desired to 

 compare results with coals from different sources. The figures given 

 in Table III have been calculated to correlate the above results with 

 the more commercial values; that is, of the above results expressed 

 on the basis of the coal as received. This table shows the relation 

 between the actual loss on carbonization expressed as a percentage 



Sec. Ill, Sig. 7 



