and of Rural Improvement generally, during 1842. 64-9 



sition in a very slow degree, especially when on or near the 

 surface of the ground. Fourcroy found that charcoal decom- 

 posed water, as having a greater affinity for oxygen than for 

 hydrogen ; and Sir Humphry Davy proved that charcoal was 

 soluble in potash and soda. From these facts it is concluded 

 that charcoal not only furnishes moisture, but, by slow decom- 

 position, carbonic acid gas. Thouin, in his Cours de Culture, 

 1827, vol. i. p. 292., says that charcoal broken in pieces is 

 favourable for chalky soils by absorbing moisture, and for absorb- 

 ing heat from being black. He confirms the fact before stated, that 

 the places on which charcoal has been burnt are extremely 

 fertile. Powdered charcoal is a more powerful manure, he 

 says, than when it is in larger pieces ; acting, however, in the 

 same manner by absorbing moisture from the air, and bringing 

 it within reach of the roots of plants. By the experiments of 

 Messrs. Allen and Pepys, charcoal was found to imbibe from 

 the atmosphere in one day about one eighth of its weight of water. 

 When recently prepared, charcoal has the remarkable property 

 of absorbing different gases and condensing them in its pores, 

 without any alteration of their properties or its own. (See 

 lire's Diet, of Chem., and of Arts, Manufactures, §*c.) Char- 

 coal ashes, Marshall, in 1800, states, are considered a good 

 manure in the Midland districts ; but these ashes arise prin- 

 cipally from the sods used in covering the heaps, and contain 

 but a very small proportion of pieces of charcoal. Arthur 

 Young, it appears {Annals of Agriculture, published in 1784 

 and 1785, vols. i. and ii. p. 139 — 169., and 254 — 272.) made 

 a great many experiments with powdered charcoal as a manure, 

 but arrived at no definitive result, except that it was inferior to 

 charcoal ashes, and still more so to wood ashes. Charcoal 

 powder, we have seen by the experiments of Lucas (see our 

 Volume for 1841), has been used successfully for striking 

 cuttings; and Liebig, referring to these experiments, says, 

 " common wood charcoal, by virtue merely of its ordinary 

 well-known properties, can completely replace vegetable mould 

 or humus. The experiments of Lucas," he adds, " spare me 

 all further remarks upon its efficacy. Plants thrive in pow- 

 dered charcoal, and may be brought to blossom and bear 

 fruit if exposed to the influence of the rain and the atmo- 

 sphere; the charcoal may be previously heated to redness. 

 Charcoal is the most ' indifferent ' and most unchangeable 

 substance known ; it may be kept for centuries without change, 

 and is therefore not subject to decomposition. The only sub- 

 stances which it can yield to plants are some salts which it 

 contains, amongst which is silicate of potash. It is known, 

 however, to possess the power of condensing gases within its 

 pores, and particularly carbonic acid ; and it is by virtue of 



