The Farmer’s Magazine 20(6): 474-479 (Dec. 1849)

CHARCOAL AND CARBONISED SUBSTANCES
BY J. TOWERS, MEMBER R.A.S., H.S. OF LONDON

It might appear intrusive and superfluous to offer further remarks upon subjects which occupy already so prominent a position; but I hope to prove that, by collecting facts which have come under my own observation, and within the range of personal experience, I may be so fortunate as to give additional impulse to the spirit of inquiry that is now active, and thus to advance the cause of science and of agriculture.

Common Wood-Charcoal claims the first notice. In 1844, I think it was on the 17th of July, I was present at the Council of the Royal Agricultural Society, the late Lord Spencer being in the chair: three or four specimens of turnips were produced by the steward or bailiff of the Earl of Essex—that nobleman himself, if I mistake not, being at the table. These turnips exhibited a great and marked difference in their growth and appearance. One sample was very fine and well developed, perhaps nearly a foot high, of a full rich green; it had been raised from seed sown in drill, the seed well mixed with twelve times its bulk of common charcoal-dust. Another and smaller specimen was raised with nine times its bulk of the same dust, and five times its weight of salt.

Since writing the above, I have fortunately discovered the original communication from the Earl, as it stands in vol. v. p. 280 of the Journal. The third specimen (No. 1 of the paper.) was produced from seed without charcoal. I now follow the printed details—(merely remarking, that on returning to Berkshire, I sowed several drills with turnip-seed and charcoal. There was then no dearth of rain, and the plants vegetated and advanced well; but the situation was unfavourable, and I did not add charcoal sufficient to render the experiment decisive):—

"All three put in the same day in drills, on the same ground which had had no manure for three years. The ground at the time (3rd June) was dry as dust; in five days Nos. 2 and 3 came up well. No 3 soon, however, taking the lead. At the end of a fortnight all were slightly watered, but the soil was so dry that No. 1 did not vegetate: 2 and 3, however, grew rapidly. At the end of five weeks we had heavy rains, and in a few days No. 1 at last appeared, and then No. 3 almost grew visibly. The three plants I exhibited to the Council this day (17th July) bore the following proportions to each other:—

I am happy to have met with this official communication, which more than confirms what my great distance from the exhibitor did not permit me to observe. The Earl further adds that he had experimented with carrots to the extent of six acres —the seeds of which, "in spite of the drought, were well up in three weeks." My object in thus adducing by-gone facts is to excite the reader's attention to the chemical difference that will be proved to exist between the ordinary charcoals of wood and the carbonised peat and other refuse matters that assuredly comprise a great multiplicity of fertilizing elements.

Lucas, of the Munichgardens (see p. 454 of this volume,) employed wood-charcoal in his floral experiments, and with machinery that I have on several occasions ventured to suggest were objectional as being far inferior to our tank-pits, heated by hot water and its vapour. I tried many experiments with charcoal alone, and in combination with leaf and heath mould, very soon after the appearance of Liebig's first book, but could not satisfy myself that the material effected any great improvement in the growth and tinting of leaves or flowers, in the Gesnerae Gloxinia and similar plants. Plants also, so treated, were liable to become dry very rapidly.

To whatever quality may be ascribed the fertilizing principle of wood-charcoal, certain it is that, when newly-made, it absorbs given quantities of gases. By the experiments of M. Theodore de Saussure it was proved that after charcoal was again heated to a red-heat, then suffered to cool under mercury, and instantly plunged into a vessel of the gas, on being taken from the mercury, it absorbed—(assuming 1 to represent a single volume of charcoal)—of

Ammoniacal gas 90.
Muriatic gas 85.
Carbonic acid gas 35.
Oxygen gas 9.25
Hydrogen 1.75
Sulphuretted hydrogen .55

It is stated also that if wood charcoal remain in contact with valerian, galbanum, balsam of Peru, or musk, it destroys their peculiar odour. This absorbent power appears to depend upon the great porosity of charcoal, which itself is produced by the action of heat. Wood is composed chiefly of the elements carbon, oxygen, hydrogen, with some salts of potassa and lime. When acted upon in iron cylinders, oxygen and hydrogen are expelled, water is formed; also some carbonaceous compounds, among which are pyroligneous, acetic acid, pyroxilic spirit, and tar; the remaining charcoal retains the exact form of the wood employed; it is, however, lighter than water, and full of pores. When thus completely decomposed, it consists chiefly of carbon, with a little silica, and the bases of the salts above alluded to.

Many years ago I discovered a process by which the carbonate of soda (sesqui-carbonate), then just coming into practical use, might be much improved. Crystals of the purest soda were exposed in flat shallow trays, having canvass bottoms, to the vapour of ignited charcoal, conveyed into oblong close leaden vessels through a leaden cylinder. The combustion was effected in iron crucibles, regulated by an air stopper. The gas developed was pure carbonic acid; it acted upon the crystals of soda, combined with the neutral salt, and displaced the water of crystallization which drained through the canvass. In the fire crucible the residue of the combustiou was very small in bulk and weight, and consisted of the silex, lime, and potassa, which constitute the impurities of common charcoal. From these, and corresponding data, we infer that wood charcoal is very inferior to the carbonized matter of peat, containing vegeto-animal matters, either in respect to depurating, deodorizing, or fertilizing properties, and therefore that the powerful and unanswerable exposé by Mr. Rogers, of the advantages to be derived from carbonized peat detailed in pp. 443-452 have not been duly appreciated by the writer of the article on "Night Soil and Peat Charcoal," which commences at page 452 of this volume. In the second column of page 453 there is a table given by Mr. Phillips, wherein we perceive that the carbon in 100 parts of that charcoal is stated to be 79.24, and yet the writer says—"We should infer that the effects would be different from that of other charcoals." So, then, although eleven other elements are tabulated, amounting in the whole to 20.76 parts, to make up the 100, many of them being essential to vegetable growth, we are to take it for granted that peat charcoal, so constituted, would differ little in its effects from common wood charcoal, although the latter consists almost entirely of carbon!

It may, perhaps, be regretted that in the comparative tables of the components of peat charcoal and English excretiae, placed side by side in second column of page 445, the quantities of each constituent is not registered; thereby more certainty would have been acquired, and the misgivings of many half friends either qualified or removed. However, as quantities must vary, whenever substances liable to perpetual changes are submitted to analysis, we ought to be content for the present with what has been effected and demonstrated. There may be difficulty in arranging the mechanism required to realize the vast objects proposed. Whatever is "the business of all and everybody—" the proverb is somewhat musty. Yet the inference, obvious as it is, leads one to hope that a project absolutely national may be taken up by the nation, and never be permitted to lapse into oblivion. Shame on the country if it be!