Page:The American Cyclopædia (1879) Volume XIII.djvu/228

 218 PEAT composition. Usually a portion of sand, which is sometimes the larger portion, is found in it. Some peats leave when burned much carbon- ate of lime ; others chiefly sulphate of lime ; others principally oxide of iron ; silicic and phosphoric acids, magnesia, potash, soda, alu- mina, and chlorine also occur in small quanti- ties in the ash of all peats. With the excep- tion of alumina, all these bodies are important ingredients of agricultural plants. Those bases (lime, oxide of iron, &c.) which are found as | carbonates or oxides in the ashes, exist in the j peat itself in combination with the humic and | other organic acids. When these compounds ' are destroyed by burning, the bases remain as carbonate. Peat is valuable as a fertilizer and as fuel. Considered as an amendment to the soil, the value of peat (usually called muck by farmers) depends upon its remarkable power of absorbing and retaining water, both as a liquid and as a vapor ; its power of absorbing ammonia; its effect in promoting the disinte- gration and solution of the mineral ingredients of the soil ; and its influence on the tempera- ture of the soil. As a direct fertilizer its value depends upon the organic matters, the inor- ganic or mineral ingredients, and the pecu- liarities attending its decay. Peat is directly applied to soils, is placed in stables as an ab- sorbent, or is composted with manures. For either of these purposes it is essential that it be exposed to the weather for six months or a year previous to being used. This " weather- ing," as it is called, by alternate freezing and thawing completely disintegrates the mass of the peat, and at the same time facilitates cer- tain chemical changes due to the action of the atmosphere, which remove the excess of or- ganic acids and otherwise render it better fit- ted for incorporation into the soil, and as food for plants. In Ireland and north European countries peat has long been extensively used as fuel. It is only within a comparatively few years that the increased cost of wood and coal in the older of the United States has directed j attention to this abundant source of combus- ; tible material. The best peat for fuel is that which is most free from undecomposed vege- table matters, which has therefore a homo- geneous brown or black aspect, and is like- wise free from admixture of earthy substances. Such peat is usually found at a considerable j depth, is unctuous when moist, shrinks greatly j in drying, and forms hard and heavy masses when dry. These are the oldest and ripest i peats, contain most carbon, and are the most j compact. The difference in weight between fresh and dry peat of any quality is very great. Fibrous peat fresh from the bog may contain 90 per cent, of water, of which 70 per cent, must evaporate before it can be called dry. The proportion of water in earthy or pitchy peat is less, but it is always large, so that from 500 to 900 Ibs. of fresh peat must be lifted in order to make 100 Ibs. of dry fuel. The quan- tity of water retained by air-dried peat and wood is about the same, 20 per cent., but in thoroughly seasoned wood or peat it may be only 15 per cent. When hot-dried the pro- portion may be 10 per cent, or less. While peat is still moist it gathers moisture from the air, and in this condition it has been known to burst the sheds in which it was stored, or even to set them on fire ; but after becoming dry to the eye and touch, it is no more affected by dampness than seasoned wood. Peat is pre- pared for use by hand and by machinery, and is also burned into charcoal and distilled for illuminating gas. It is prepared by hand as follows : The surface material, which from the action of the elements has been pulverized to muck and is full of roots and undecomposed matter, must be removed usually to the depth of a foot or more; a deep ditch is then run from an outlet a short distance into the peat bed, and the working goes on from its banks. It is important that system be followed in rais- ing the peat, or there will be great waste of fuel and of labor. A "field " is next laid off about 20 ft. square, by making vertical thrusts with a sharp spade in parallel lines, as far apart as the breadth of the sods, 4 or 5 in. It is then cut at right angles the length of the sods, 18 or 20 in. The sods are lifted by horizontal thrusts of the spade at a depth of 3 in., and are placed on a light barrow or board and carried off to the drying ground, where they are laid flatwise to drain and dry. In Ireland it is the custom, after the peats have lain thus for a fortnight, to place them on end close together, and after further drying the sods are built up into stacks about 12 or 15 ft. long, and 4 ft. wide at the bottom, narrowing at the top, with a height of 4 to 5 ft. The outer turfs are inclined so as to shed the rain. In these "clamps" on the bog the peat often remains until wanted for use. In Germany it is common to excavate by vertical thrusts of the tool represented in fig. 1. The three sides of this cut as many sides of the block, the bottom being torn out, or a second workman in the ditch cuts out the blocks of a proper thickness by horizontal thrusts of a sharp spade. In Ireland the " slane " is employed, a common form of which is seen in fig. 2, it being a long narrow spade, 20 x 6 in., with a wing at right an- gles to the blade. In north Prussia the peat-cutting ma- chine of Brosowsky is ex- tensively employed. It con- sists of a cutter like the four sides of a box, with oblique edges, which by a crank and rack work is forced down into the peat perhaps 20 ft. It can cut only upon the edge of an excavation, and when it has penetrated sufficiently a blade FIG. 1. German Peat Knife.