﻿PROXIMATE ANALYSIS OF COALS. 



45 



same length of time over the flame inclosed in a cylindrical asbestos shield. 

 With this exception the samples received the same treatment in detail. 

 The results are as follows : 



Total volatile matter, per cent 



(1) 

 50.27 



(2) 



50.22 



(3) 

 50.26 



(4) 



50.21 



A very satisfactory shield is that shown in the figure. It is 12 centi- 

 meters long and 6 centimeters in diameter. The platinum triangle is 

 placed on top of the shield so that only about half of the crucible is 

 surrounded. The height of the crucible from the top of the burner is 

 controlled by the cubical blocks. 



Fig. 1. 



In all of the following experiments, platinum crucibles of 20 cubic 

 centimeters' capacity and weighing 20 grams were used. The crucible 

 covers must fit perfectly, but this is always possible since the edges of a 

 crucible can be hammered smooth and round on a cone and the lids can 

 be pressed into shape by placing the top down on a flat ground surface. 

 The coal was pulverized to pass a sixty-mesh sieve. Where determina- 

 tions of the ash are given, they were made on the same portion of the 

 coal as was used for the volatile matter, consequently mechanical losses 

 are indicated by variations in the percentage, for determinations of the 

 ash admit of great accuracy if performed with due care. 



The first sample, an air-dried coal from the southeastern end of Bo I mi 

 Island j No. 4, gave the following results : 



the official method: 





Per 



cent. 





Moisture 



15.41 



15.42 



(15.42) 



(15.42 



Volatile combustible matter 



41.52 



41.83 



43.05 



41.73 



Fixed carbon 





38.95. 



37.75 





Ash 





3.80 



3.78 





100.00 



100.00 



