ASHES, the remains of anything burned, whether of vegetable or animal origin, and to a certain extent of mineral bodies also.
Vegetable ashes. Ashes vary in composition according to the nature of the plant, the soil in which it grows, and the manure used upon it. The substances usually contained in the ashes of land plants are potash, soda, lime, magnesia, silica, the oxides of iron and of manganese, chlorine, carbonic acid, sul phuric acid, and phosphoric acid. Alumina occurs rarely, and sometimes oxide of copper I has been met with. Very frequently more than one half of the ashes of vegetables con sists of carbonate of lime. The quantity of ashes varies, not only according to the soil, age, and aspect of the plant, but also in dif ferent Parts of the same plant, from 2 to per cent. of its weight, after drying in the air. The soluble part of wood ashes consists of the alkaline sulphates, carbonates, and chlorides; while the insoluble matter is chiefly composed of carbonate of lime, and probably of magnesia, phosphate of lime, and phosphate of iron.
The incineration of wood is a most im portant operation ; from its ashes are obtained the immense quantities of impure potash, and the carbonate called pearlash, imported from America and other countries. The sap of plants contains also other vegetable acids, as the oxalic, citric, tartaric, malic, &c.; and the salts which these form with potash are de composed by heat, and yield the carbonate. The ashes of land plants yield principally the salts of potash, such as barilla—those of ma rine plants afford a large quantity of soda salts, and especially the carbonate, such as kelp.
Coal ashes are extremely various both in their appearance and composition. Thus, much of the coal of the north of England, under common circumstances, burns to a cin der, which is a mixture of the ashes of the coal with some carbonaceous matter requiring rather a high temperature to burn it, on account of its being enveloped by incombus tible matter. The coal of Somersetshire burns
to red ashes, evidently coloured by peroxide of iron : those of the Staffordshire coal are nearly white. The quantity of ashes yielded by dif ferent kinds of coal varies considerably ; ac cording to Kirwan, Wigan coal contains 1.57 per cent. of ashes ; Whitebaven coal 1.7, and Swansea coal 3.33 per cent.; they consist prin cipally of silica and alumina, with small quan tities of lime, sometimes magnesia, and also peroxide of iron ; but they do not contain either the chlorides, phosphates, or alkaline salts found in wood-ashes. Peat ashes differ chemically from both the other kinds.
Animal ashes resulting from the burning of bones and other animal solids, consist princi pally of phosphate of lime, with traces of salts of lime, magnesia, and soda.
Mineral ashes, such as those of Vesuvius, as examined by Vauquelin, were grayish in colour; they were tasteless, and found to consist of alumina, oxide of iron, muriate of ammonia, sulphate of lime, potash, copper, manganese, lime, and charcoal. Vauquelin also analyzed the ashes ejected in the same year from dEtna; they were of a gray colour, and in fine pow der ; they contained sulphur, sulphates of lime, copper, and alumina, and several other mineral ingredients.
The ashes of domestic economy, comprising not only the coal-ash from the grate, but a quantity of dust and miscellaneous fragments, are a valuable commercial article. The ash heap of a (lust contractor has a large money value, for much of the waste serves as mate rial for manufactures.