Chemistry, inorganic and organic : with experiments / by Charles Loudon Bloxam.

  • Bloxam, Charles Loudon, 1831-1887.
Date:
1875
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry, inorganic and organic : with experiments / by Charles Loudon Bloxam. Source: Wellcome Collection.

    652/708 (page 624)
    sion were made for the restoration of the constituents of plants, after death, to the atmosphere and soil, where they might afford food to new genera- tions of plants. Accordingly, very shortly after the death of a plant, if sufficient moisture be present, the changeable nitrogenised (albuminous) constituents begin to putrefy, and chemical motion being thus excited, is communicated to the other parts of the plant, under the form of decay, so that the plant is slowly consumed by the atmospheric oxygen, its carbon being reconverted into carbonic acid, its hydrogen into water, and its nitrogen into ammonia, these substances being then transported in the atmosphere to living plants which need them, while the mineral consti- tuents of the dead plants are washed into the soil by the rain. Moist wood is slowly converted by decay into a brown substance, which has been called 7JM??^?^s, and forms the chief part of -the organic matter in soils. Alkalies dissolve this substance, and on the addition of an acid to the brown solution, a brown precipitate is obtained, which is said to contain humic, ulmic, and geic acids, but these substances do not crystal- lise, and their existence as definite acids appears to be somewhat doubt- ful. Two other acids of a similar kind, crenic and ajgocrenic acids (Kpi]vrj, a well), have been obtained from the same source, and are also found occasionally in mineral waters, When it is desired to jDreserve wood from decay, it is impregnated with some substance which shall form an unchangeable compound with the albuminous constituents of the sap, Kreasote (page 457) and corrosive sublimate (Jcyanising) are occasionally used for this purpose, the wood being made to imbibe a diluted solution of the preservative, either by being soaked in it or under pressure. In Boucherie's process for preserving wood, the natural asQending force of the sap is ingeniously turned to account in drawing up the preservative solution. A large incision being made around the lower part of the trunk of the growing tree, a trough of clay is built up around it, and filled with a weak solution of sulphate of copper, acetate of iron, or chloride of calcium. Even after the tree has been felled, it may be made to imbibe the pre- serving solution, whilst in a horizontal position, by enclosing the base of the trunk in an impermeable bag suppHed with the liquid from a reservoir. The impregnation of the wood with such solutions not only prevents chemical decay, but renders it less liable to the attack^ of insects and the growth of fungi. NUTEITION OF ANIMALS. 441. Between the chemistry of vegetable and that of animal life there is this fundamental distinction, that the former is eminently constructive and the latter destructive. The plant, supplied with compounds of the simplest kind—carbonic acid, water, and ammonia—constructs such com- plex substances as albumen and sugar; whilst the animal, incapable of deriving sustenance from the simpler compounds, being fed with those of a more complex character, converts them eventually, for the most part, into the very materials with which the constructive work of the plant commenced. It is indeed true, that some of the substances deposited in the animal frame, such as fibrine and gelatinous matter, rival in com- plexity many of the products of vegetable life ; but for the elaboration of the substances, the animal must receive food somewhat approach- ing them in chemical composition. It is to this nearer resemblance