PEAT. A fibrous earth, the remains of the decomposition of aquatic grasses, in a transition state toward the formation of coal. Localities where found, are termed peat bogs, and when other fuel is scarce it is commonly used, burning with a clear flame or smouldering, according to its quality. It is cut, with a peculiarly shaped tool, in the form of large bricks, and after being thoroughly dried, is stored away for use. Peat is not common in the United States on account of the rarity of the peculiar swamps where it is found. In northern Indiana, and in some por tions of Wisconsin, there are rather extensive bogs of peat, but the cheapness of other fuel renders its use unprofitable. Probably the abundance and cheapness of wood and coal in the United States has prevented the develop ment of the resources of our peat bogs. Peat, according to various analyses, presents a general similarity in composition, the difference in qual ity being sand of accidental mixture. Air-dried peat usually contains from fifty to sixty per cent. of carbon, although the best samples reach
seventy-five per cent. Thus from one and a quar ter to one and a half tons of peat should be equal to a ton of good coal. The top of the best peat bog is always composed of a spongy mass, con sisting of decaying vegetable matter, roots, etc. ; deeper it becomes more and more homogeneous in its nature, until, at length, all trace of vege table structure is lost, and we find a dense black mass of hard and compact peat, ranging in specific gravity when dried, from that of water to considerably less. That near the top of the bog may not have a specific gravity of more than 0.28, but some dense Irish peats have shown a specific gravity of 1,058. In curing peat it is essential that it be thoroughly dried, since if moist, it will generate heat, and undergo spon taneous combustion. The same fact is observed in some of our soft coals that become air-slaked, and thus take fire.