Section of Charcoal Pit
The charcoal is extracted by means of a specially constructed rake resembling a light drag, but having much finer teeth, which, after it has become quite cold, is stored in a shed until required for use.
The very finest charcoal, superior to what is generally sold, is produced by this method. The expenses connected with making it are, however, a little heavier than usual, owing to the slower system of charring, the use of larger wood, and the extra cost of covering with turf. As to the cost of producing charcoal by the above method, this will vary greatly, much depending on the distance the wood has to be carted and on the cost of labour in the particular district.
The price paid to the charcoal burners is 7d. per bushel, or about four guineas per ton, which may seem high, but when we consider that it is specialized work that is confined to few and attended with grave risks and discomfort, the amount earned is not excessive. It should also be remembered that, previous to lighting the kilns, sufficient rough, not corded, wood has to be sawn and split and the pits carefully built and covered, not to speak of the constant attention required, both day and night, wet or dry, for from three to seven days, during charring process. The usual price for burning charcoal when the wood is corded is 35s. per ton.
Fresh-felled wood is rarely converted into charcoal, the greater portion of that used being thinnings of the previous season. The proportion of wood to charcoal varies greatly, much depending on the size, quality, and maturity of timber. Having had occasion to purchase charcoal lately, I found the price, retail, to be 2s. 6d. per bushel, or in quantities of not less than a ton, £14, for that of fair quality.
From about the twelfth century onwards Scotland, where wood was abundant, produced annually a large quantity of charcoal iron; and in 1660 the Navy Commissioners nominated John Evelyn to investigate the then denudation of forests owing to the manufacture of charcoal for iron smelting, and the following quaint extract from his report will be interesting:—“Nature has thought fit to produce this wasting ore more plentifully in woodlands than any other point, and to enrich our forests to their own destruction—a deep execration of iron mills and ironmasters also.” The Lorn Works, in Argyllshire, were started in 1753, and annually consumed upwards of 3,000 tons of lump charcoal.
The Sussex and Kentish forests at one time supported many of the familiar charcoal burners, and right brawny and thrifty were these denizens of the woodland with their rustic wooden huts and piles of rifted firewood, but the industry was almost a thing of the past till again called into active existence by the exigencies of the war.
Kiln burning.—The kiln is made of brick, one course being sufficient, if bands of iron be added to strengthen the brickwork. It is usually conical in shape, 24 ft. in diameter, with an equal height, and holds about forty cords of wood. The wall of the kiln is carried up nearly straight for about 6 ft., when it is gradually drawn in and made a blunt cone shape. A plate of iron is fastened on the top in the manner of a stone to an arch. Three-inch hoop-iron bands, about an eighth of an inch thick, are placed around the kiln and drawn together by means of screw-bolts and nuts. At the base, and near the top, are double sheet-iron doors, by which it is filled with wood or emptied of charcoal. The time required to fill, burn and empty is about three weeks. Pit-burning, for estate purposes, is, however, most commonly pursued, and has this advantage—that the charcoal can be made at any place where timber is being felled, without extra expense, save that of the cartage of the charcoal, whereas in using the kiln or retort the wood must, in most cases, be conveyed to the place where it is erected.
Comparative Value of Woods for Charcoal making.—Amongst home-grown timber, oak, ash, and beech are generally preferred for charcoal making, but the following table will show pretty correctly the proportionate relative values of the various descriptions of wood for gunpowder charcoal:—
| Per Cent. | |
| Rhamnus frangula contains | 27 |
| Laburnum | 25 |
| Boxwood | 24 |
| Sweet Chestnut | 23 |
| Oak | 22 |
| Holly | 20 |
| Walnut | 20 |
| Beech | 19 |
| Sycamore | 19 |
| Elm | 19 |
| Willow | 18 |
| Poplar | 18 |
| Birch | 17 |
| Alder | 17 |
| Ash | 17 |
| Hazel | 17 |
| Mountain Ash | 17 |
| Scotch fir | 16 |
| Larch | 16 |
Uses of Charcoal.—The uses of charcoal for estate purposes are very numerous, for horticultural, agricultural and other departments. From remote antiquity charcoal has been used as a fuel, and for many purposes it is still unsurpassed. It is by far the cleanest solid fuel known; it burns steadily, gives out a great amount of heat, and lasts well. On account of its smokelessness it is invaluable for cookery, and it is also admirably suited for use in green-house and other stoves. It is not adopted for heating apartments on account of the poisonous gas (carbonic oxide) produced in its combustion, and the danger, most apparent when the charcoal is burnt in an open chauffer, is not obviated by using it in a stove, as carbonic oxide has the power of diffusing through red-hot iron.
In gardening, charcoal is largely used for potting purposes, for vine borders, and for flower beds; and in the form of dust it is the best material for packing bulbs for transmission to a distance.
Perhaps the most important of the uses to which charcoal can be put about a house or estate is that depending on its extraordinary power of absorbing gases. It is a perfect deodorant, a preservative of food and all animal substances and a valuable disinfectant. The gases most readily absorbed by charcoal are those which are most prejudicial to health and most frequently produced by putrefactive changes.
In the pores of the charcoal they are destroyed by union with the oxygen condensed from the air. The fact of its being absolutely non-poisonous and perfectly odourless puts it before all other disinfectants.
“Dogwood” for Gunpowder Charcoal.—The alder buckthorn, berry-bearing or black alder (Rhamnus frangula) is a native shrub that is fairly plentiful in Southern England, though rare in Scotland and Ireland. Confusion sometimes arises from the same popular name being applied to widely different species of plants, and this, unfortunately, is the case with the shrub in question. What is known among gunpowder manufacturers as dogwood is in reality the present shrub (Rhamnus), which, however, is quite distinct from the true dogwood (Cornus) and belongs to an entirely different family. To those who contemplate growing charcoal wood for the making of explosives, this distinction is of the utmost importance, as I have seen Cornus sanguinea cultivated for the making of gunpowder.
The alder buckthorn is perfectly hardy, growing freely even in the North of Scotland, where it ripens its seeds. It is usually found as an erect-growing bush from 8 ft. to 10 ft. in height, though in suitable situations in Southern England specimens fully 20 ft. high, with stems 6 in. in diameter, are to be met with. The bright green leaves are oval in shape and vary, according to conditions of growth, from 2 in. to 3 in. in length, while the flowers are of a dull yellowish green and are succeeded by dark purple berries each about the size of a pea. From a very early date the alder buckthorn has been cultivated, though not extensively, in this country for charcoal making, and the price, upwards of £15 per ton, that is paid for the wood, shows that the growing of this shrub is a profitable undertaking. At one time large quantities of the wood were produced in Sussex and other counties, the selling price being £14 per ton when peeled and tied in bundles.
The cultivation of the alder buckthorn is nearly similar to that of the osier for basket-making, and the produce is dealt with and disposed of in like manner. For soil any good loam inclined to be dampish will suit it well, and an open, but not wind-swept, situation should be chosen for its cultivation. The land intended for growing the alder buckthorn should be trenched the winter before planting, and a top-dressing of leaf soil or thoroughly decomposed manure, the former preferably, will greatly assist the growth of the young plants and prevent too speedy evaporation of moisture from the soil. Young plants are not offered in quantity in our nursery catalogues, and in order to obtain a stock sufficient to form a plantation, seed-sowing or layering old plants must be resorted to. Fortunately, by either method the plant is readily obtained in quantity, and as the seeds are produced in fair abundance and ripen freely this method of getting up a stock is to be recommended.
The berries, after being collected in the early winter, are treated much as we treat those of the yew and holly. They are mixed with sand in order to separate the seed and fleshy covering, and the whole is sown during early spring in previously prepared beds. The seed beds may be prepared in any shady situation out of doors, the soil being largely composed of light sandy loam mixed with finely riddled leaf-mould. Sometimes the seeds are sown in boxes and placed in a cool frame, but we have found cultivation out of doors more satisfactory. When two years old, the seedlings should be transplanted into lines 18 in. apart and 9 in. from plant to plant. Here they may remain for another two years, after which they should be planted out permanently and headed back the following season. Rather thick final planting is to be recommended, as the shrub being of upright growth, requires comparatively small room for development, and the best wands are produced by a close order of growth, say 5 ft. from plant to plant.
Layering does not produce such upright-habited shrubs as those grown from seed, and the yield of wood per acre under exactly similar conditions of growth is greatly in favour of seedlings.
After planting, the ground should be kept free from rough-growing seeds for the first two years, the crop being cut at from six to seven years’ growth, when the wands are from 1½ in. to 2 in. diameter at butt end. Cutting and bundling is usually done by contract, but, as with the osier, it is imperative that the crop be cut over near ground level and short “stumps” without “spurs” encouraged.
As in the case of ordinary coppice wood, the buckthorn for charcoal making may be cut every sixth or seventh year, the straightest shoots when sorted in about 5 ft. lengths being tied in bundles which are about a yard in girth. The buckthorn being a gross feeder, manuring the land after the removal of a crop has been found advantageous.
Although largely imported from Holland, and other parts of the Continent, home-grown wood is preferred, as it produces a much superior charcoal for the manufacture of explosives. Unfortunately, however, home supplies are so limited that foreign wood is imported in considerable quantity, and as there was a scarcity before the war, the probabilities are that, with our greatly increased consumption of charcoal explosives, a dearth of suitable wood is now being felt.
With the present small remuneration attaching to the cultivation of coppice or underwood, which under ordinary circumstances does not exceed £4 per acre, the cultivation of the alder buckthorn is to be recommended, particularly as the price is at least quadrupled. The cultivation of this is quite simple, while the quality of soil required need not be better than that which produces a crop of chestnut or hazel. In cultivating the alder buckthorn for charcoal purposes the following rules should be observed:—
1. It will not succeed satisfactorily in sandy, poor or water-logged soils; rich, well-manured loam being preferred.
2. The ground should either be trenched or ploughed and cleared of all rough-growing weeds the winter before planting.
3. Plant seedlings or layers in the spring in lines about 5 ft. apart and the same distance from plant to plant.
4. An annual clearance of weeds and loosening of the soil between the rows of plants is recommended where a heavy crop is expected.
5. Induce the growth of stout clean shoots by liberal feeding and clean cultivation.
6. Cut the shoots close to the ground so as to prevent the formation of long spurs and minimize the number of off-shoots. Clean cutting with a sharp tool is imperative.
7. After the removal of a crop, stirring and enriching the soil is to be recommended.
8. Though found mixed with undershrubs and in the shade of trees when in a wild state, yet the greatest quantity of the most valuable wood for charcoal making is produced in open situations.