Page:The American Cyclopædia (1879) Volume II.djvu/13

 THE AMERICAN CYCLOPAEDIA. ASHES A SHES, the solid remains after the burning of J. combustible substances. When a vegeta- ble or animal substance is burned with free ac- cess of air, part of it is resolved into volatile compounds, chiefly water, carbonic acid, and free nitrogen, while the other and generally the smaller portion is left as incombustible residue or ash. If the substance be decomposed with exclusion of the air, a different set of compounds results; and the residue may be charcoal, bone black, or some other substance, depending upon the nature of the material taken for the ex- periment. Of wood ashes, even the different parts of the same plant furnish different quanti- ties, and ashes of different compositions. The soil itself has an influence upon the kind and amount of materials taken up by the plants. Nearly all the substances found in the soil enter into the composition of vegetable matters, and are found in their ashes. Alumina is, however, very rarely met with. No inorganic substances found in the ashes of plants come from any other source but the soil. Of the portion of wood ashes soluble in water, and removed from them by leaching or lixiviatipn, the greater part consists of the carbonate, silicate, sulphate, and chloride of potassium. Of the insoluble portion (leached ashes), carbonate of lime commonly forms about one half; the remainder is mostly silicate and phosphate of lime, oxide of iron, and salts of magnesia. . It is not supposed that the bases were combined with carbonic acid in the plants, but with organic acids, and that these were replaced by carbonic acid in the process of combustion. Plants that grow in and near salt water contain soda instead of potassa, deriving it from sea salt. The following ex- amples show how the quantity of ashes varies with the wood : From 1,000 parts by weight of oak, well dried, Kirwan obtained of ashes 13-5 parts ; from elm, 23 -5 ; willow, 28 ; poplar, 12-2; ash, 5'8; pine, 3-4. The bark furnishes more ashes than the solid wood, and the branches than the trunk. Peat and coal ashes contain a large proportion of alumina ; oxide of iron, carbonate and sulphate of lime, are also found in them. The principal uses of wood ashes are for making soaps and for enriching land. The soluble salts of potash are dissolved out from them, and oil or fatty matters added to the alkali, to produce the soap. The residue is a valuable manure, but evidently inferior to the ashes before the potash was extracted. Pot and pearl ashes are the salts of potash extract- ed from wood ashes. The name potash is traced to the method of its preparation from the extract of the ashes boiled down in iron pots. Barilla, or soda ash, is a similar product of sea plants, soda replacing the potash. It was for- merly largely imported into this country, but is now excluded by cheaper preparations of soda direct from sea salt. Ashes are some- times used with lime and sand to increase the strength of mortar, and prevent its cracking. Bone ashes contain much phosphate of lime, the cause of the fertilizing properties of bones. Phosphoric acid and phosphorus are prepared from these ashes. They are also used to make the cupels in which argentiferous lead is melt- ed and oxidized for obtaining the pure silver. The cupels are merely bone ashes made into a paste with water, or beer and water, and then moulded and dried. In distilleries, ashes find an extensive use for the rectification of the alcoholic liquors, the alkaline matters neutral- izing any acids that may be present, and thus preventing then- volatilization. It is a com- mon impression that their great consumption in American distilleries is to give strength to the liquors after their dilution with water, and this is confirmed by the violent caustic quality, not unlike that of the ley of ashes, for which much of the common whiskey of the country is remarkable. Ashes mixed with salt make a strong cement for iron pipes. Cracked pipes repaired with it bear as heavy pressure as new pipes. The cement sets on application of heat of 600. Shower of Ashes, a phenomenon