g4 Historical Sketch of Improvements in [Aug. 



that the arrangement of them which I have given (see Annals of 

 Philosophy, xiv. 81, and xv. 394), founded upon the chemical 

 constitution of each, but recognized hkewise by the consumers, 

 possesses some vakie, and will considerably facilitate future inqui- 

 ries into the nature and properties of this most important com- 

 bustible. I have divided pit coal into five different species ; 

 namely : 



(1.) Kilkenny coal, which burns without flame, and cannot be 

 coked. 



(2.) Caking coal, which melts when heated, and then sticks 

 together in large solid masses. It abounds in the counties of 

 Durham and Newcastle, from which places it is carried to every 

 part of the east and south coast of Great Britain. 



(3.) Splint coal distinguished by the difficulty with which it 

 breaks, and by the higher temperature necessary to set it on tire, 

 but burning well when once kindled, and answering well for the 

 manufacture of coke. 



(4.) Cherry coal which has much of the aspect and friability 

 of the caking coal ; but possesses more beauty, and is easily 

 distinguished by its not melting when heated. It abounds in 

 Staffordshire, and in various parts of Scotland. 



(6.) Cannel coal easily distinguished from the other kinds by 

 its not soihng the fingers, by its beirvg susceptible of polish, and 

 of being cut into boxes, inkhorns, and other similar trinkets. It 

 catches fire like a piece of wood, and burns like a candle. 



The composition of these different kinds of coal is as follows : 



(1.) Kilkenny coal contains only carbon and oxygen in the 

 proportion of 35 atoms of the former to two of the latter ; so 

 that its composition may be represented thus : 



35 atoms carbon = 26-25 



2 atoms oxygen = 2-00 



28-25 



The three next kinds of coal contain carbon, hydrogen, azote, 



and oxygen ; but cannel coal appears to contain no oxygen, but 



to be a compound of carbon, hydrogen, and azote. Caking coal 



contains the least hydrogen compared to the quantity of carbon. 



In caking coal there are 3 atoms carbon for 1 atom hydrogen 



sphnt coal there are 2 1 



cherry coal there are 1 1 



cannel coal there are 1 2 



The following table exhibits the number of atoms of each 

 constituent in each of these four kinds of coal : 



Atoms. Atoms. Atoms. Atoms. 



Caking coal. 33 carbon + 11 hydrogen + 3 azote + 1*5 oxygen 

 Splint coal .. 28 +14 +1 +3-5 



Cherry coal .34 + 34 ' +2 +1-0 



Cannelcoal.il +22 +1 +0-0 



