OF THE EASTERN BORDERS. 315 



and an insect here and there fluttered on the wing : — yet the thought- 

 ful mind, connecting this scene with the distant Future, feels deeply 

 interested with its aspect and hearings ; for here the AUwise Creator, 

 who adjusts the working of physical laws to the attainment of moral 

 purposes, caused the vegetative powers of nature to put forth their 

 strength, to make provision for the future wants of the intellectual 

 and moral beings who were to people the world. 



It now remains for us to attempt to explain the chemical changes 

 which the entombed vegetable mass has undergone in its conversion 

 into coal. 



Coal is formed of the same elements as wood, but in different pro- 

 portions. Leaving out unessential materials, wood is composed of 

 oxygen and hydrogen gases united vrith about an equal quantity of 

 carbon. Oak, for example, contains 49'432 parts of carbon, 44 '499 

 of oxygen, and 6'069 of hydrogen. Now when wood is immersed 

 in water, a change commences which Liebig calls mouldering, and 

 which is different from the decay which results when air is freely ad- 

 mitted ; oxygen and hydrogen are given off in combination with 

 smaller quantities of carbon, the hydrogen and carbon forming car- 

 buretted hydrogen, the fire-damp of miners, and the oxygen and 

 carbon forming carbonic acid, the choke-damp of miners. Trees sub- 

 merged in bogs are undergoing this change ; and, hence, the swamps 

 bordering the Mississippi are constantly emitting carburetted hydro- 

 gen, especially wherever the ground is dug into. Bog-wood, there- 

 fore, contains a larger proportion of carbon than wood does, its com- 

 position being 57"0 of carbon, 37'5 of oxygen, and 5'9 of hydrogen. 

 When the mouldering process has gone on for a longer period, 

 lignite, such as is found in the tertiary beds, is formed, in which the 

 carbon is further increased, the composition being 5 8 -.5 6 of carbon, 

 26-85 of oxygen, and 5' 95 of hydrogen. As we go backward in 

 time, the disproportion becomes greater, for the rich bituminous 

 Bensham coal belonging to the Newcastle coal-measures, consists of 

 86'44 of carbon, and only of 5'67 of oxygen and 5'74 of hydrogen. 

 And in anthracite, where the series of changes is nearly completed, 

 the oxygen and hydrogen have all but disappeared, and the result is 

 nearly pure carbon. 



Here a practical hint may be given. Some persons, especially 

 those living in the country, expose coals to rain, in the belief that 

 their quality will be thereby improved; but exposure to moisture 

 hastens on the decay of coal ; it cannot, indeed, be stored in too dry 

 a situation. For steam vessels, dry storage is of great importance, 

 because access of moisture, besides wasting coal, may cause spon- 

 taneous combustion, when sulphuret of iron is in combination with 

 the coal. 



The mouldering process is still going on in coal-fields, for to this 

 is owing the evolution of carburetted hydrogen, the dreadful enemy 

 to miners ; and yet this destructive element, when rightly treated, 

 ministers to our wants, cooking our food and lighting our villages 

 and towns. Bearing in mind what has already been achieved in con- 



