The peat is dry enough for pressing when, after forming in the hands to a ball, it will not firmly retain this shape, but on being let fall to the ground, breaks to powder. The entire cost of preparing 1000 peats for use, or market, was 2 Thalers, or $1.40. Thirty peats, or "stones" as they are called from their hardness, have the bulk of two cubic feet, and weigh 160 lbs. The cost of preparing a hundred weight, was therefore, (in 1859,) four Silver-groschen, or about 10 cents.
The stamp is of simple construction, somewhat like a pile driver, the mould and face of the ram being made of cast iron. The above process is not applicable to _fibrous peat_.
The two methods to be next described, are similar to the last mentioned, save that the peat is _hot-pressed_.
_Gwynne's Method._--In 1853, Gwynne of London, patented machinery and a method for condensing peat for fuel. His process consisted, first, in rapidly drying and pulverizing the fresh peat by a centrifugal machine, or by passing between rollers, and subsequent exposure to heat in revolving cylinders; and, second, in compressing the dry peat-powder in a powerful press at a high temperature, about 180° F. By this heat it is claimed, that the peat is not only thoroughly dried, but is likewise partially decomposed; _bituminous matters being developed, which cement the particles to a hard dense mass_. Gwynne's machinery was expensive and complicated, and although an excellent fuel was produced, the process appears not to have been carried put on the large scale with pecuniary success.
A specimen of so-called "Peat coal" in the author's possession, made in Massachusetts some years ago, under Gwynne's patent, appears to consist of pulverized peat, prepared as above described; but contains an admixture of rosin. It must have been an excellent fuel, but could not at that time compete with coal in this country.
[Illustration: Fig. 5.--EXTER'S DRYING OVEN.]
[Illustration: Fig. 6.--EXTER'S DRYING OVEN.]
In 1856, Exter, of Bavaria, carried into operation on an extensive scale, a plan of preparing peat-fuel in some respects not unlike the last mentioned method. Exter's works, belonging to the Bavarian Government, are on the Haspelmoor, situated between Augsburg and Munich. According to Ruehlmann, who examined them at the command of the Hanoverian Government in 1857, the method is as follows:--1. The bog is laid dry by drains and the surface is cleared of bushes, roots, and grass-turf, down to good peat. 2. The peat is broken up superficially to the depth of about one inch, by a gang of three plows, propelled by a portable steam engine. 3. The peat is further pulverized by a harrow, drawn by a yoke of oxen. 4. In two or three days after harrowing, the peat is turned by an implement like our cultivator, this process being repeated at suitable intervals. 5. The fine and air-dry peat is gathered together by scrapers, and loaded into wagons; then drawn by rope connected with the engine, to the press or magazine. 6. If needful, the peat, thus collected, is further pulverized by passing it through toothed rollers. 7. The fine peat is now introduced into a complicated drying oven, see figures 5 and 6. It falls through the opening _T_, and is moved by means of the spirals along the horizontal floors _O_, _O_, falling from one to another until it emerges at _Q_. The floors, _O_, _O_, are made by wide and thin iron chambers, through which passes waste steam from an engine. The oven is heated further by hot air, which circulates through the canals _K_, _K_. The peat occupies about one hour in its passage through the oven and falls from _Q_, into the press, having a temperature of from 120° to 140°Fahrenheit. The press employed at Staltach is essentially the same as that now used at the Kolbermoor, and figured on p. 125. It is a powerful eccentric of simple construction, and turns out continuously 40 finished peats per minute. These occupy about one-fourth the space of the peat before pressing, the cubic foot weighing about 72 lbs. The peats are 7 inches long, 3 inches wide, and one half to three quarters of an inch thick, each weighing three quarters of a pound. Three presses furnish annually 180,000 cwt. of condensed peat, which is used exclusively for firing locomotives. Its specific gravity is 1.14, and its quality as fuel is excellent. Ruehlmann estimated its cost, at Haspelmoor in 1857, at 8-1/2 Kreuzers, or a little more than 6 cents per cwt., and calculated that by adopting certain obvious improvements, and substituting steam power for the labor of men and cattle, the cost might be reduced to 6-1/2 Kreuzers, or a little more than 4 cents per cwt.