328 



FORMATION OF PEAT. 



In the first volume of Dr. Macculloch's valuable " History of the 

 Western Islands of Scotland," he has given a luminous description 

 of the formation of peat, which completes the natural history of peat 

 moss. Beside the Sphagnum palustre, he has enumerated nearly 

 forty plants which concur to the generation of peat. 



The process by which these vegetables are converted into peat, is 

 most clearly seen in the sphagnum. As the lower extremity of the 

 plant dies, the upper sends forth fresh roots like most of the mosses, 

 the individual thus becoming in a manner immortal, and supplying a 

 perpetual fund of decomposing vegetable matter. A similar process, 

 though less distinct, takes place in many of the rushes and grasses, 

 the ancient roots dying together with the outer leaves, while an an- 

 nual renovation of both, perpetuates the existence of the plant. The 

 growth of peat, necessarily keeps pace with that of the vegetables 

 from which it is formed ; hence the necessity of replacing the living 

 turf on the bog where peat has been cut, — a condition now required 

 in all leases, in which liberty to cut turf is included. On the con- 

 version of vegetable matter into peat. Dr. Macculloch observes : — 

 " Where the living plant is still in contact with peat, the roots of the 

 rushes, and ligneous vegetables, are found vacillating between life 

 and death, in a spongy half decomposed mass., Lower down, the 

 pulverized carbonaceous matter is seen mixed with similar fibres, 

 still resisting decomposition. These gradually disappear, and at 

 length a finely powdered substance alone is found, the process being 

 completed by the total destruction of all the organized bodies." — P. 

 130. The best peat is that of which the decomposition is most com- 

 plete, and the specific gravity and compactness the greatest. The 

 quality of peat, Dr. Macculloch observes, is much affected by the 

 wetness or dryness of the soil, and the elevation or other causes, 

 which influence the temperature and moisture of the atmosphere. 



For a description of the chemical changes produced in peat by 

 water and fire, I must refer to the first volume of Dr. Macculloch's 

 work before quoted, p. 131. It is only in the first stages of decom- 

 position that peat is soluble, and communicates a dark colour to 

 water. 



The rapid formation of peat in many situations, where it is found 

 covering ground that was formerly pastured, admits of an easy ex- 

 planation, since Dr. Macculloch has so clearly described the mode in 

 which this substance is generated. 



The property possessed by peat of preserving animal matter from 

 putrefaction is well deserving notice. It is probably owing to this, 

 that some of the fleshy parts of the mastodon have been so long pre- 

 served in peat bogs. 



In the Philosophical Transactions, 1734, there is a letter from Dr. 

 Balguy, giving an account of the preservation of two human bodies 

 in peat for fifty-nine years. "On January 14, 1675, a farmer and 

 his maid-servant were crossing the peat moors above Hope, near 



