A new system of vegetable physiology : designed to account satisfactorily for the phenomena which take place in the vegetable kingdom, and to shew the influence of heat, light, and electricity on vegetation / by Daniel Vaughan.

  • Vaughan, Daniel, 1821-1879.
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: A new system of vegetable physiology : designed to account satisfactorily for the phenomena which take place in the vegetable kingdom, and to shew the influence of heat, light, and electricity on vegetation / by Daniel Vaughan. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    found to deprive it of the greater part of this gas, which, it is general- ly supposed, has been dissipated in the air. But, since water, at its mean temperature and pressure, is capable of holding its own volume of carbonic acid in solution, the loss must be ascribed to a different cause. In the water which runs from springs, there may be observed a kind of green slime, the production of which does not appear to be, in any manner, connected with vegetation. This is carbonaceous matter, formed by the decomposition of the carbonic acid contained in the water. Its quantity appears increased, as the water is more strong- ly impregnated with carbonic acid, or subjected to circumstances which promote rapid evaporation ,* a fact which leaves no doubt res- pecting its origin. 17. A similar deposit may be observed in streams, at those places where evaporation takes place with great rapidity—as on mill-dams and water-falls—where it is accelerated by the agitation of the water and the dashing of it into spray. A great part of the carbonic acid, thus decomposed, is derived from the air. In observing the course of rivulets, I have often been struck with the fact, that the greatest quan- tity of this carbonaceous matter is deposited in places where the water tumbles over rocks, and suffers the greatest agitation—places, indeed, fery unfavorable for a deposit of any substances dissolved or suspend- ed in water, and still more unfavorable for the reception of seeds. This proves that the formation of the substance is due to evaporation, the continuation of which produces insolubility, and causes it to be depos- ited in places where it occurs. It may, perhaps, serve as a food to fishes ; and the Confervas, which are found attached to rocks in running streams—if they are to be regarded as plants—derive their food from the same source. The formation of the compound known by the name of Crenic and Apocrenic Acid, Humin Geine, &c, which are found in springs, owe their origin to the cause I have explained, and may be considered modifications of the same substance. 18. Every attentive observer of these, and other facts, may readily conceive that the decomposition of carbonic acid, which must result from the continual evaporation from the surface of the earth, is quite adequate to form all the humus or vegetable mould of the soil, and to supply the waste attending vegetation. On marshy, wet lands, where this process is seldom interrupted, the greatest quantity of carbonace- ous mould* generally occurs. We should, no doubt, find the fertility increased in the same proportion, if the continual evaporation did not render the greater part of this mould insoluble, diminish its tendency to decomposition, and thus impair, or perhaps, destroy its fertilizing * The term carbonaceous mould, and olher term-applied to this peculiar sub- stance, are not intended to convey the idea that it consists entirely of carbon. Jt also contains a large portion of oxygen and hydrogen. Its formation may be supposed to consist in the union of carbonic acid and water, with the separation of a large portion of oxygen. Whether this oxygen is derived from the water, or from the carbonic acid, is a question which might appear difficult to be deci. tied. But the fact, that oxygen and hydrogen occur nearly in the proportion in which they form water, must lead us to suppose that it is derived from the acid, though in many instances the water also undergoes decomposition,