Mr. T. Richardson upon the Composition of Coal. 121 



the iodine by bromine or even chlorine ; and I have indeed 

 myself commenced some experiments with a view to this re- 

 search. 



XVII. Researches upon the Composition of Coal. By Mr. 

 Thomas Richardson.* 



[Illustrated by Plate III.] 



TylT'E are at present in possession of various analyses of coal, 

 ' ' but at the time when these were made the method of 

 analysis was too imperfect to enable any chemist to obtain ac- 

 curate results. This fact, with the great and important use 

 made of coal in manufactures, induced me to undertake the 

 present researches. They have been conducted with every 

 possible care and attention, and throughout I have been in- 

 debted to the kind instruction and advice of Professor Liebig. 

 In the first part of the present memoir the various methods 

 employed in determining the different constituents will be 

 shortly described ; and in the second part, the analyses of the 

 various coals, &c. 



I. METHODS EMPLOYED IN DETERMINING THE DIFFERENT 

 CONSTITUENTS. 



Hygrometric Moisture, S^c. 



The first object was to determine the amount of water which 

 the coal contained, and whether this water was chemically 

 combined, or merely hygrometrical. With this view the fol- 

 lowing experiments were made : 



1 . A certain quantity of coal, finely powdered, was dried at 

 100° C by means of Professor Liebig's apparatus, and the loss 

 amounted to r23 per cent. 2. -SS-i grm.f coal, as finely 

 pounded as the preceding, was dried in a chloride of zinc bath 

 at the temperature of 185° C when it sustained a loss of '0105 

 or 1*229 per cent. 



It may, therefore, be concluded that if coal contains water, 

 it must exist in a state of the most intimate chemical combi- 

 nation. 



Ashes. 



The determination of the ashes was very simple. A weighed 

 quantity of coal was heated to redness in a small platina cru- 

 cible, till the whole of the carbon was oxidized, and the resi- 

 due constituted the amount of ashes contained in the specimen. 



• From the Transactions of the Natural History Society of Newcastle- 

 upon-Tyne, vol. ii. p. 401. 



t The measure of quantity used in these analyses is the French gramme ; 

 1 gramme French = 15*433 grains English. 



