Part 10 (1/2)

It thus appears that peat which is light, loose in structure, and much mixed with clay or sand, is a poor or very poor article for producing heat: while a dense pure peat is very good.

A great drawback to the usefulness of most kinds of peat-fuel, lies in their great friability. This property renders them unable to endure transportation. The blocks of peat which are commonly used in most parts of Germany as fuel, break and crumble in handling, so that they cannot be carried far without great waste. Besides, when put into a stove, there can only go on a slow smouldering combustion as would happen in cut tobacco or saw-dust. A free-burning fuel must exist in compact lumps or blocks, which so retain their form and solidity, as to admit of a rapid draught of air through the burning ma.s.s.

The bulkiness of ordinary peat fuel, as compared with hard wood, and especially with coal, likewise renders transportation costly, especially by water, where freights are charged by bulk and not by weight, and renders storage an item of great expense.

The chief value of that peat fuel, which is simply cut from the bog, and dried without artificial condensation, must be for the domestic use of the farmer or villager who owns a supply of it not far from his dwelling, and can employ his own time in getting it out. Though worth perhaps much less cord for cord when dry than hard wood, it may be cheaper for home consumption than fuel brought from a distance.

Various processes have been devised for preparing peat, with a view to bringing it into a condition of density and toughness, sufficient to obviate its usual faults, and make it compare with wood or even with coal in heating power.

The efforts in this direction have met with abundant success as regards producing a good fuel. In many cases, however, the cost of preparation has been too great to warrant the general adoption of these processes.

We shall recur to this subject on a subsequent page, and give an account of the methods that have been proposed or employed for the manufacture of condensed peat fuel.

2.--_Density of Peat._

The apparent[10] specific gravity of peat in the air-dry state, ranges from 0.11 to 1.03. In other words, a full cubic foot weighs from one-tenth as much as, to slightly more than a cubic foot of water, = 62-1/3 lbs. Peat, which has a specific gravity of but 0.25, may be and is employed as fuel. A full cubic foot of it will weigh about 16 lbs. In Germany, the cubic foot of ”good ordinary peat” in blocks,[11] ranges from 15 to 25 lbs. in weight, and is employed for domestic purposes. The heavier peat, weighing 30 or more lbs. per cubic foot in blocks, is used for manufacturing and metallurgical purposes, and for firing locomotives.

Karmarsch has carefully investigated more than 100 peats belonging to the kingdom of Hanover, with reference to their heating effect. He cla.s.sifies them as follows:--

A. _Turfy peat_, (_Rasentorf_,) consisting of slightly decomposed mosses and other peat-producing plants, having a yellow or yellowish-brown color, very soft, spongy and elastic, sp. gr. 0.11 to 0.26, the full English cubic foot weighing from 7 to 16 lbs.

B. _Fibrous peat_, unripe peat, which is brown or black in color, less elastic than turfy peat, the fibres either of moss, gra.s.s, roots, leaves, or wood, distinguishable by the eye, but brittle, and easily broken; sp. gr. 0.24 to 0.67, the weight of a full cubic foot being from 15 to 42 lbs.

C. _Earthy peat._--Nearly or altogether dest.i.tute of fibrous structure, drying to earth-like ma.s.ses which break with more or less difficulty, giving l.u.s.treless surfaces of fracture; sp. gr. 0.41 to 0.90, the full cubic foot weighing, accordingly, from 25 to 56 lbs.

D. _Pitchy peat_, (_Pechtorf_,) dense; when dry, hard; often resisting the blows of a hammer, breaking with a smooth, sometimes l.u.s.trous fracture, into sharp-angled pieces. Sp. gr. 0.62 to 1.03, the full cubic foot weighing from 38 to 55 lbs.

In Kane and Sullivan's examination of 27 kinds of Irish peat, the specific gravities ranged from 0.274 to 1.058.

3.--_Heating power of peat as compared with wood and anthracite._

Karmarsch found that in absolute heating effect

100 lbs. of turfy, air-dry peat, on the average = 95 lbs. of pine wood.

” fibrous ” ” ” = 108 ” ”

” earthy ” ” ” = 104 ” ”

” pitchy ” ” ” = 111 ” ”

The comparison of heating power by bulk, instead of weight, is as follows:--

100 cubic ft. of turfy peat, on the average[12] = 33 cubic ft. of pine wood, in sticks.

” ” fibrous ” ” = 90 cubic ft. of pine wood, in sticks.

” ” earthy ” ” = 145 cubic ft. of pine wood, in sticks.

” ” pitchy ” ” = 184 cubic ft. of pine wood, in sticks.

According to Brix, the weight per English cord and relative heating effect of several air-dry peats--the heating power of an equal bulk of oak wood being taken at 100 as a standard--are as follows, _bulk for bulk_:[13]

_Weight per _Heating cord._ effect._ Oak wood 4150 lbs. 100 Peat from Linum, 1st quality, dense and pitchy 3400 ” 70 ” ” 2d ” fibrous 2900 ” 55 ” ” 3d ” turfy 2270 ” 53 Peat from Buechsenfeld, 1st quality, pitchy, very hard and heavy 3400 lbs. 74 Peat from Buechsenfeld, 2d quality 2730 ” 64