Phosphorus, long known as a chemical rarity costlier than gold, but at present one of the most extensively used of chemicals, is prepared from bones. However, bones can only be regarded as organs of collection, as originally it is derived from the earth. Phosphorus is not found in a native or un-combined state, since its affinity for oxygen is v!Jry great. United with this latter element it mostly forms phosphoric acid, which again is met with in union with such bases as soda, lime, magnesia, etc. These compounds are termed phosphates, and are widely distributed over the globe, although they rarely occur in large masses on one spot. They occur in the soil—in most limestones, and in many clays and marls—which fact accounts for their value as fertilizers. Nearly all iron ores contain traces of phosphates; these are reduced in the process of smelting, phosphorus being set free; hence its presence in cast iron, wrought iron, and steel. The excellent “Russian iron from the furnaces of Prince “Demidoff, near Nischnet-agilsk, according to Schafhautl, owes its qualities to a trace of phosphorus. ' Still, this admixture is not always desirable, since, if exceeding certain limits, it makes the iron coldshort. Phosphorus is also a component part of our own body ; it exists there not only as phosphoric acid, but also in a de-oxidized condition united with organic substances; as, for instance,^ the fatty matters ofthe brain, whence the well-known sentence of Moleschott, “ No thought without phosphorus !” —a sentence, it may be stated, that has been the subject of considerable abuse. However, it is not only in the brain that phosphorus is met with, for, according to Ronalds, a part of the phosphorus of the urine, from which this element had first been separated, occurs also united with an organic compound. How does the phosphorus pass into the human body ? Through plants especially. To them the part has been assigned to withdraw it from the soil and to prepare it for the food of man. Before phosphorus was known to exist in the animal kingdom, its presence in plants had been considered as an acknowledged fact; indeed, phosphorus was found in them before it had been ascertained in the urine of man. The number of vegetables greatly increased in which the element in question was met with; it remained unknown for a long time that it had to be ranked among their constituent parts, and even when this could no longer be doubted, its origin remained an enigma. Although Fownes had already stated that many volcanic minerals contained phosphorus, this assertion was not regarded as true. To modern times it was reserved to throw light upon this subject. In the molybdate of ammonia, chemistry now possesses an exceedingly sensitive reagent for phosphoric acid, which is so very important for the growth of plants. It has been ascertained by Forch-hammer that a soil in which phosphoric acid can scarcely be detected, contains of this material not less than 700 pounds per acre, to a depth of one foot. Is it therefore surprising that phosphates occur so frequently in mineral springs and rivers? It seems that the phosphates in plants serve especially for the formation of the albuminous bodies, that are so all-important for the building up of the human framework. With regard to the wandering of phosphorus in plants, we present the fol lowing interesting facts of Corenwinder : Young plants always yield ashes rich in phosphorus. How ever, after the maturity of the seeds or fruits (for which phosphoric acid is especially needed), the sterns and leaves are found to contain only traces of this acid ; and when all the seeds have reached perfect maturity, the stems, leaves, and roots are generally devoid of phosphorus. This element appears to occur in an intimate combination with the albuminous principles of vegetables. Indeed, if these are dissolved with water or other liquid, the phosphates pass also into solution, while they become insoluble, when the albuminates are coagulated by boiling water. The vegetable organs which lack phosphorus, seem also to be free of albuminous substances, at least not a trace of phosphates could be met with in the woody pericarp of certain fruits, as in the almonds and hazelnuts, the ashes of which yield principally silica and lime. The exudates of plants generally contain no phosphoric, acid ; at least slich is the case with manna and gum-arabic. It is known that in exhausting the pulp of young roots with water, fibrin is obtained, which contains pectose and the in-crusting substances. It follows, therefore, that the skeleton of vegetables owes its solidity not to the phosphates,as is the case with that of the animals. The leaves that remain in the forests during winter yield ashes rich in iron, silica, and lime, but free of phosphorus. It is also worthy of note that, although analysis has as yet failed to discover phosphates in the sea, the maritime plants contain considerable quantities of this substance. Corenwinder, at least, lias searched in vain for phosphoric acid in the water of the North Sea, as well as in the boiler sediments of vessels crossing the ocean. The pollards of flowers and the spores of cryptogams are rich in acid of phosphorus ; this being especially the case with the pollards of Lilittm candidum. It is remarkable that the ashes of pollards and those of the semen of animals are nearly alike in their component parts, they being both rich in phosphoric acid ! From all we know, it is certain that the presence of phosphates in plants is necessary to the formation of the organic substances in question. For agriculture it would belpghlv important to know whether there exists a relation between the quantities of the phosphates and those of the albumen oids, but unfortunately very little is known about this subject, and it will demand manifold and extensive researches before satisfactory information will be obtained. But such researches are very desirable, for it should be the duty of agri culturists to look rather to the production of highly albumi nous matters, than to endeavor to bring certain organs of plants to a high state of development without regard to their nutritive value.
This article was originally published with the title "The Wandering of Phosphorus in Plants" in Scientific American 21, 16, 249 (October 1869)