Ashes, the remains of animal and vegetable bodies after burning. It is not strictly correct to speak of the ashes of a mineral. When lead, for instance, is exposed to heat, it turns to dross, which has the appearance of ashes, but is merely the lead combined with oxygen. In the same way, volcanic ashes, as they are called, are only a finer kind of pumice-stone, the solidified scum of molten lava. The ashes of organic substances destroyed by fire consist of the fixed salts contained in these substances. In land-plants, the most important are salts of potash, along with silica and lime; in sea-plants, soda takes the place of potash. By lixiviation of the ashes, the potash or soda is dissolved and separated from the insoluble mass, and is then purified by crystallisation. The ashes of sea-plants contain also more or less iodine. Peat and turf ashes contain, besides alkalies, more or less clay and sand; the same is true of pit-coal, which sometimes contains iron.
At one time the ashes or inorganic ingredients of plants were considered unessential to their existence. But the progress of vegetable chemistry has taught that a certain proportion of saline food is absolutely necessary to the development of plants. The analysis of the ashes of the different kinds of vegetable substances has since become of great interest.
The ashes of animal bodies do not differ greatly from those of vegetables. Bone-ashes consist essentially of lime united with phosphoric acid. This bone-earth is very valuable as manure for grain. In well-wooded countries, ashes from burnt wood form an article of considerable trade. They are much used in the processes of soap-boiling, bleaching, dyeing, glass-making, &c. Wood-ashes are also used in washing and other domestic processes, as a cheap preparation of Potash (q.v.), better known under the names American ashes or pearl-ash.
The presence or absence of ashes is frequently a most important factor in deciding as to the adulteration of articles of commerce. Thus if a sample of milk, flour, mustard, or other substance, on being dried and incinerated, with the necessary precautions, yields more ash than is normally present, it is strong evidence of adulteration, and the analyst can then apply his tests to the ashes obtained, and so determine the nature of the substance which has been added. For volcanic ash, see VOLCANO.