DR. ANGUS SMITH ON PEAT, 283 



and growing one ton and a fifth per annum, it would re- 

 quire forty-five years. Considering the rapidity of growth 

 of surface-plants on some peat-bogs, we cannot suppose it 

 less, when not removed by cattle or otherwise. Now, as 

 peat will hold something like eighty per cent, of water, or 

 even more, we may fairly allow in the same time five inches 

 of peat to have grown, considered roughly equal to one inch 

 of wood. On the other hand, we know that grass and other 

 plants may be stimulated so that several crops may be ob- 

 tained in the year — under favourable circumstances, let us 

 say, three. We might thus have in some places five, and in 

 others fifteen inches of soft peat in forty-five years, accord- 

 ing as the peat-plants were ill or well fed. We must divide 

 the peat into two classes (some purposes require more) — the 

 fibrous (which is fresh or not very old), and the amorphous. 

 The rapid growth can apply to the first only ; the true black 

 peat, burning with much flame, is much older, and we can- 

 not vet calculate the time for its formation. In order to 

 form it, a decay goes on, which consists of oxidation of the 

 carbon mainly, whilst the (higher) hydrogen compounds 

 remain and proportionally increase. The carbonaceous 

 matters are carried away in considerable quantities in the 

 brown water. This lost quantity is not easily calculated. 

 Some peat-water has two grains in it, some less than one. 

 If we supposed one grain per gallon, and thirty-six inches 

 of rainfall, Ave should require to subtract 1 15 lbs. or about 

 1 cwt. per acre per year (and with seventy-two inches twice 

 as much) for removal by water. When the peat is fibrous, 

 there is no decay perceptible, and the growth may be taken 

 without deduction. In some cases the plants remain 

 nearly fresh, I believe, for centuries. In a lake-dwelling 

 of which I am going to speak, the plants below the hearth- 

 stone and the floor appeared only slightly yellow. Still 

 the decay is needful for the conversion to true peat. If 

 the plant is well protected from air, and from flowing 



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