416 



THE FARMER'S MAGAZINE. 



obtain their carbon, if not from the atmosphere ? 

 and yet we make no return of carbon for all that 

 we take from them. Successive crops of charcoal 

 have been burnt and removed from the mountain 

 regions, where the trees can find little humus, and 

 can return only to the soil their foliage to decay 

 and make more ; the cattle pasturing on the prairies 

 must remove immense quantities of carbon in their 

 tissues — the supply to the trees, grasses and weeds 

 has been kept up from the atmosphere un- 

 doubtedly. 



We are told that the northern provinces of 

 Holland export a million pounds of nitrogen 

 annually in their cheese — this must have been 

 taken into the organisms of the cows, from the 

 ground, through the grasses upon which they feed. 

 Man makes no compensation for this. Whence 

 can it come ? undoubtedly from the atmosphere, 

 which is the great medium through which it is 

 silently conveyed from the great craters of volcanoes 

 that pour out with their molten lavas invisible 

 streams also of carbonate of ammonia. 



Boussingault's experiments, which were con- 

 ducted on a large scale, confirm these views— he 

 had them continued on one spot during 21 years ; 

 he carefully weighed all the manure applied, and 

 all the crops harvested, and the quantity of carbon, 

 hydrogen, oxygen, nitrogen, and ashes, of both 

 manure and crop, were carefully estimated in the 

 whole of both, by means of chemical anaylsis. 

 Now for the result : the annual harvest, on an 

 average, gained twice as much nitrogen, three times 

 as much carbon and hydrogen, and four times as 

 much oxygen, as had been applied to the soil in 

 manure. 



Here we find the value and the beauty of the 

 science of chemistry and its application to practice 

 — this depends too upon what chemists call the 

 law of proportions, which may be thus stated : 

 Each element or different kind of simple matter 

 will combine with others in certain definite pro- 

 portions—thus, carbonic acid, a compound, is 

 always composed of oxygen and carbon, in the 

 proportions of 16 by weight of the former, united 

 with 6 of the latter substance or element. Am- 

 monia always contains 3 of hydrogen with 14 

 nitrogen; but, referring to the experiments of 

 Boussingault, and believing that carbonic acid, 

 ammonia, and water, are the food of plants, we 

 find that they contain more oxygen than is needed 

 for the plants— more than their tissues contain ; 

 hence we infer that oxygen must be set free— a 

 fact long ago discovered by absolute experiment, 

 and verified by every tyro in chemistry — and 

 here we have another beautiful proof of the wisdom 

 of the arrangement. This oxygen, necessary for 

 animal life, as it is the great supporter of res- 

 piration, and equally necessary to combustion, is 

 eUminated by plant life, and sent to renew and 

 purify the atmosphere by the very plants that had 

 first removed the noxious compounds from the air : 



Carbonic acid \ ^W" ^^ 2 



f Carbon 6 1 



Water J" Oxygen 8 1 



L Hydrogen 1 ^ 1 



Ammonia . . . J gy^^^" ^ 3 



(Nitrogen 14 ,14 



Here we find a grand exchange or interchange 

 of elements of matter between the three great 

 kingdoms of nature. " Decomposition and the 

 process of respiration set free all vegetable and 

 animal substances (diminishing the amount of 

 oxygen in the air), in the form of carbonic acid, 

 ammonia and water, which diffuse themselves in 

 the atmosphere. The plant takes possession of 

 these substances, and forms from them (accom- 

 panied by an incessant increase of the oxygen of 

 the atmosphere) some compounds that are rich in 

 carbon and hydrogen, but devoid of nitrogen, such 

 as starch, gum, sugar, and the various fatty matters, 

 and others that are rich in nitrogen, namely, al- 

 bumen, fibrine, and casein. These compounds 

 are for the service of the animal, which builds up 

 its corporeal frame from the latter and burnt the 

 former in the respiratory process, for maintenance 

 of the necessary heat. This theory stands now, 

 firm and unshakeable upon the facts which have 

 been brought forward, and the naturalist is per- 

 fectly correct when he says, that man, through the 

 mediation of plants, in the first instance, lives upon 

 air. Or, we may express it in this way : the plant 

 collects matters from the atmosphere, and com- 

 pounds from them the food of man ; but life itself 

 is only a process of combustion, of which decom- 

 position is the final conclusion. Through this 

 combustion all the constituents return back into 

 the air, and only a small quantity of ashes remains 

 to the earth, from whence it came. But from these 

 slow, invisible flames, rises a new-born Phoenix, 

 the immortal soul, into regions where our science 

 has no longer any value."* 



Humus is however a most valuable element of 

 soils, being carbon in a state of minute division ; 

 as carbon it is almost indestructible; as carbon it 

 does not ajjpear to be taken up by plants ; its im- 

 portant role is to absorb water from the atmos- 

 phere, and to absorb and retain for the use of 

 plants — to which it readily yields them — the car- 

 bonic acid and the ammonia from the air : in this 

 power it appears to have no equal. Humus, there- 

 fore, always contains water and those gaseous 

 matters which are the food of plants, and when- 

 ever it yields up a portion to growing vegetation, 

 it absorbs fresh supplies from the atmosphere. 

 This humus is therefore not the food of plants, as 

 was formerly supposed, but it is the food bearer, 

 the storehouse or pantry, holding the gaseous food 

 of plants. 



Other elements are needed by plants as food, 

 however — mineral elements— that do not come 

 from the atmosphere, but from the soil itself; 

 hence we find a flora peculiar to certain regions, 

 and some plants that are never found in other soils 

 than those peculiarly adapted to them. So also 

 with our manures ; they must be selected in ac- 

 cordance with the peculiar wants of the crops to 

 which they are to be applied, and with the particu- 

 lar composition of the soil upon which they are to 

 be sown. This is the basis of agricultural chemistry, 

 and by its aid, if properly conducted, we learn not 

 only the elements contained by any given soil, 

 but those substances that appear to be the ne- 



* Schleiden— The Plant, p. 152. 



