

GASES. 



And then, with regard to the carbonic acid 

 and the carburetted and sulphuretted hydrogen 

 gases evolved during the putrefaction of ani- 

 mal and vegetable manures, the discoveries of 

 the chemist are equally instructive and con- 

 firmatory of the observations of the intelligent 

 farmer. The one finds that these gases, so 

 grateful to the farmer's crops, are the most co- 

 piously emitted in the early stages of putrefac- 

 tion ; that these gradually decrease in volume 

 as the fermentation proceeds ; and finally, when 

 the mass is reduced to the state of vegetable 

 mould, cease altogether. Now, the farmer is 

 well aware that the manure of the farm-yard, 

 in common with all organic decomposing fer- 

 tilizers, is by far the most advantageously ap- 

 plied, and produces the most permanent good 

 effect when it is used in the freshest state that 

 is at all compatible with the destruction of the 

 seeds of weeds, with which such collections 

 usually abound. He is aware, that in all situa- 

 tions where the gases of putrefaction are emit- 

 ted, such as near to stables, marsh-ditches, 

 covered drains, &c., that there vegetation of 

 all kinds indicates by its rank luxuriance that 

 some unusual supply of nutriment is afforded; 

 the gardener in his best arranged hot-beds no- 

 tices that the gases which ascend from his piles 

 of litter through the earth (which earth is not 

 in immediate contact with the dung) produce 

 the same effects long after all the wnrmih of 

 putrefaction has subsided. The growth < 

 of his plants is in this way stimulated, he says, 

 in an extraordinary manner. These facts and 

 observations are entirely confirmed by those 

 of the chemist He notices that all the gases 

 of putrefaction are precisely those which are 

 the most nourishing to the growth of plants; 

 that air which has been spoiled by the presence 

 of the gases evolved in putrefaction, or by the 

 breathing of animals, is exactly that which is 

 the most grateful to vegetation ; and that where 

 these gases are applied to the roots of plants 

 in the most skilful manner, so as to insure a 

 regular, steady supply, that then the plant is 

 enabled to vegetate in a most vigorous and 

 unusual manner. Thus, when green manures, 

 such as sea-weed, buckwheat, leaves of trees, 

 fern, &c., the most slowly decomposing of all 

 vegetable manures, are applied to the roots of 

 plants, the effects, according to chemical expe- 

 riments, are excellent; and, as I have else- 

 where observed, the farmer assures us that 

 they are so. He tells us that all green manures 

 cannot be employed in too fresh a state ; that 

 the best corn is grown where the richest turf 

 has preceded it ; and that where the roots, 

 stalks, and other remains of a good crop of red 

 clover have been ploughed in, that there an 

 excellent crop of wheat may be expected ; and 

 that when buckwheat is ploughed into the soil, 

 this is most advantageously done when the 

 crop is coming into flower. The chemist 

 again explains this without any difficulty. Davy 

 and other chemists have shown that when the 

 flower is beginning to appear, then the plant 

 contains the largest quantity of easily soluble 

 and decomposable matters; and that when 

 these green plants are in this state buried in 

 the soil, their fermentation is checked and gra- 

 dual, so that their soluble or elastic matters 



GASES. 



are readily absorbed by the succeeding crop, 

 and every portion of it becomes subservient to 

 the demands of other plants. No cultivator, 

 perhaps, ever examined this question more 

 accurately, or tried his experiments with more 

 neatness, than the late excellent President of 

 the London Horticultural Society, the lamented 

 Knight of Downton ; and these were the more 

 valuable, from being instituted to ascertain the 

 state of decomposition in which decaying ve- 

 getable substances could be employed most 

 advantageously to afford food to living plants. 

 This he clearly proved, however erroneous 

 were his explanations of his own observations 

 and discoveries. One of his experiments with 

 a seedling plum tree was very remarkable. He 

 placed it in a garden-pot, having previously 

 filled the bottom of it with a mixture of the liv- 

 ing leaves and roots of various grasses, covered 

 over with a stratum of mould. The plant ap- 

 peared above the surface of the ground in April, 

 and, during its growth in the summer, was 

 three times removed to larger pots in the green- 

 house, in every case the bottom of them being 

 filled as at first with living grasses, covered 

 over with a layer of mould ; and by the end of 

 October its roots occupied a space of about 

 one-third of a square foot, it having then at- 

 tained the extraordinary height of nine feet 

 seven inches. This experiment was varied by 

 Mr. Knight in several ways : he drilled turnip- 

 seed over n>ws manured with green fern leaves, 

 and compared the produce with other rows of 

 turnips by their side, manured with rich vege- 

 table mould; and in all cases those which 

 grew over the gradually fermenting green tern 

 not only grew more rapidly than those treated in 

 any other manner, but they were distinguished 

 from all others in the same field by their deep 

 green colour. Now, when the gases of putre- 

 faction are mixed with the roots of all growing 

 crops, this is exactly the effect produced. The 

 most foul, stinking water, even when transpa- 

 rent, is ever the most grateful to plants ; that 

 from stagnant ditches, which has always a pe- 

 culiar taste from the carburetted hydrogen it 

 contains, is excellent. Every gardener prefers 

 that from ponds, however clear ; the purer 

 water from wells, he tells you, is very inferior, 

 it is too cold ; but then he confesses that even 

 warming it does not render it equal to that from 

 stagnant places in its effects upon his plants ; 

 so that, in whichever way the experiment is 

 made, there is no doubt of the value of these 

 gases to the cultivator's crops, and he will rea- 

 dily therefore agree with Knight in the conclu- 

 sion, that any given quantity of vegetable mat- 

 ter can generally be employed in its recent and 

 organized state with much more advantage 

 than where it has been decomposed, " and no 

 inconsiderable portion of its component parts 

 have been dissipated and lost during the pro- 

 gress of the putrefactive fermentation." (Trans 

 Hort. Soc. vol. i. p. 248.) 



Jlqueous Atmospheric Vapour. The last sub 

 stance ever present in the atmosphere in con 

 siderable proportions, and which bears a very 

 important relation to the prosperity of tho 

 farmer's crop, is the aqueous vapour, without 

 whose unvaried presence no commonly culti- 

 vated plant could flourish, and few exist at all 



525 



