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

  • Charles Bloxam
Date:
1875
Catalogue details

Licence: Public Domain Mark

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

    658/708 (page 630)
    putrefaction of theTanimal, and then serve in their turn as sustenance for animals whose respiration supplies the air with carbonic acid, and takes in exchange the oxygen eliminated by the plant, The functions of the two divisions of animate nature are, therefore, perfectly reciprocal, and this relationship must be regarded as the founda- tion of economical agriculture. If it were possible to prevent the change of the atmosphere, it is quite conceivable that a perpetual succession of plants and animals could be raised upon a given farm without any importation of food, provided that there was also no exportation. Or even, permitting an exportation of food, the succession of plants and animals raised upon the same land might be, at least, a very long one, if the solid and liquid excrements of the animals, to feed whom this exportation took place, were restored to the land upon which this food was raised. The explanation of this is, that the solid and liquid excrements of the animal contain a very large propor- tion of the mineral constituents of the soil, in the very state in which they are best fitted for assimilation by the crop, and as long as the soil contains the requisite supply of mineral food, the plant can derive its organic constituents from the atmosphere itself. Forasmuch, however, as the vegetable and animal food produced upon a farm is generally exported to feed the dwellers in townSj whose excre- ments cannot, without excessive outlay, be returned to the soil whence the food was derived, it becomes necessary for the agriculturist to pur- chase farm-yard manure, guano, &c., in order to prevent the exhaustion of his soil. A great manufacturing country, in which the majority of the inhabitants are congregated in very large numbers around a few centres of industry, at a distance from the land under tillage, is thus of necessity dependent for a considerable proportion of its food upon more thinly populated countries where manufactures do not flourish, to which it ex- ports in return the produce of the labour which it feeds. The parts of the frames of animals differ very considerably in their tendency to putrefaction. The blood and muscular flesh undergo this change most readily, as being the most complex parts of the body, whilst the fat remains unchanged for a much longer period, and the bones and hair will also resist putrefaction for a great length of time. The comparative stability, of the fat is observed in the bodies of animals which have been buried for some time in a very wet situation, when they are often found converted almost entirely into a mass of adipocere, con- sisting of the stearic and margaric acids derived from the fat. When an animal body is thoroughly dried, it may be preserved un- changed for any length of time, and this is the simplest of the methods adopted for the preservation of animal food, becoming far more efficacious when combined with the use of some antiseptic substance such as salt, sugar, spice, or kreasote. The preservative effects of salt and sugar are sometimes ascribed to the attraction exerted by them upon moisture, which they withdraw from the flesh, whilst spices owe their antiseptic power to the essential oils, which appear to have a specific action in arresting fermentative change, a char- acter which also belongs to kreasote, carbolic acid, and probably to other substances which occur in the smoke of wood, M'ell known for its eflicacy in curing animal matter. A process commonly adopted for the preservation of animsil and vege- table food, consists in heating them with a little water in tin canisters,