CHAPTER XII.

SEAWEED AND ITS USES.

Various uses of Seaweed-Seawrack for packing and upholstery-For manure -Kelp and iodine-Carrageen moss-Seaweed for food-Large employment in China and Japan -Gelose-Other applications of seaweed.

SEAWEEDS are largely employed in Europe and the extreme East in industry, agriculture, and manufactures.

The marine plants are of much more importance than is generally supposed, and it is doubtful whether they may not yet be further utilized to advantage. Liebig, in his "Familiar Letters on Chemistry," says, "Every one knows that in the immense, yet limited, expanse of the ocean, whole worlds of plants and animals are mutually dependent upon, and successive to, each other. The animals obtain their constituent elements from the plants, and restore them to the water in their original form, when they again serve as nourishment to a new generation of plants. The oxygen which marine animals withdraw in their respiration from the air, dissolved in sea water, is returned to the water by the vital process of sea plants; that air is richer in oxygen than atmospheric air, containing 32 to 33 per cent., while the latter only contains 21 per cent. The oxygen

now combines with the products of the putrefaction of dead animal bodies, changes their carbon into carbonic acid, their hydrogen into water, while their nitrogen assumes

again the form of ammonia. Thus we observe that in the ocean a circulation takes place without the addition or subtraction of any element, unlimited in duration although limited in extent, inasmuch as, in a confined space, the nourishment of plants exists in a limited quantity."

We well know that the marine plants cannot derive a supply of humus for nourishment through their roots. Look at the great sea-tangle, the Fucus giganteus. This plant, according to Cook, reaches a height of 360 feet, and a single specimen, with its immense ramifications, nourishes thousands of marine animals; yet its root is a small body, no larger than the fist. What nourishment can this draw from a naked rock, upon the surface of which there is no perceptible change? It is quite obvious that these plants require only a hold-a fastening, to prevent a change of place as a counterpoise to their specific gravity, which is less than that of the medium in which they float. That medium provides the necessary nourishment, and presents it to the surface of every part of the plant. Sea water contains not only carbonic acid and ammonia, but the alkaline and earthy phosphates and carbonates required by these plants for their growth, and which we always find as constant constituents of their ashes.

Seaweeds or fuci are used directly as manure, for the manufacture of soda, iodine, bromine, and some like Irish moss, etc., for the manufacture of gelose. Dried and pressed seaweeds are also used for ornamental or botanical purposes. In Scotland and other northern countries seaweed is used in winter for feeding horses, cattle, and sheep, and is eaten by deer when other food is scarce.

The beneficial effects in scrofulous swellings and goitre of the vegetable ethrops and of the sponge charcoal, which had been introduced by Armand de Villeneuve near

the close of the thirteenth century, and the discovery of iodine in the ashes of sea plants, induced Dr. Coindet, of Geneva, in 1819 to study the effects of iodine, and led to the introduction of that element into medicine.

The Fucus vesiculosus, Lin., grows on rocky shores of the Atlantic on or near high-water mark. Formerly it was known by the name of Quercus marina or sea-oak, its common English names being bladder-wrack, sea-wrack, sea-ware, kelp-ware, and black tang. Of late the bladderwrack seems to have been employed to some extent medicinally in the United States. It has also been employed in France in the form of extract, by exhausting the plant with 54 per cent. of alcohol.

There are two species in which a considerable trade is carried on-a lichen, and the sea-wrack or Zostera marina, vulgarly known there under the name of "pailleule," which have become considerable sources of profit to the inhabitants. The moss or lichen is used by chemists. and for making gummy preparations, and is even forwarded to Belgium. The Zostera marina is largely used for stuffing beds and chairs by packers and upholsterers, under the name of crin vegetal-in England, “alva.” In 1873 over 4,100,000 lbs. of this dried weed were sent from Granville by land and sea. As this quantity represents about two-thirds of the whole sale, the total may be approximatively estimated at about £2,000 in value. The Zostera has the habit of the seaweeds, although belonging to another natural order.

Algæ and fuci are the scientific names given to various marine plants which grow at the bottom of the sea. They are collected on the coasts in different parts of the world, where they are found at certain periods of the year, driven by the currents and thrown on the beach by the waves and tides.

Many persons may think it strange that we should Occupy ourselves with plants which flourish in the sea, when we possess so many useful plants on the land. To this it may be replied that very little is known of the considerable commerce which is carried on in various parts of the world, more especially in the far East. Hence we propose to publish, for general information, some reliable details bearing upon this subject.*

In France, on the coasts of Normandy and Brittany— at Noirmontier for instance-large quantities of seaweed are collected. It is generally the species known to naturalists under the name of Fucus cornosus. There large numbers live entirely on the result of the harvest of seaweed they collect each year. The seaweeds are largely employed for industrial purposes. Upholsterers and others use them for stuffing couches, stools, etc., in which they too frequently are substituted for horsehair. They are used to stuff mattresses, especially beds for children, because their aromatic odour keeps away insects. Packers use seaweed for wrapping fragile objects. Chemists obtain from them. a number of valuable products, such as saline matters or soda, chlorides, sulphates, silicates, iodine, bromine, etc.

At the last Maritime Exhibition held in Paris, seaweeds were shown dyed various tints after decolouration. This new application was to replace paper cuttings, the price of which, owing to numerous uses, had much advanced. The seaweeds, after drying, are pressed into bales of about 100 kilogrammes. The colour is brown, something like dried tobacco.

Employment of Seaweed for Manure.-The Chinese and

*We quote from an interesting article on the uses of seaweed, published in the "Bulletin de la Société d'Acclimatation of Paris" for March, 1878, by M. E. Renard.

Japanese from time immemorial have recognized the value of seaweeds in agriculture; but as the population of those countries became more numerous, and the adoption of the algæ as a healthy food became better known, they attained a higher value, and their employment as a fertilizer was to a great extent replaced by other substances, especially the excreta of towns. In Japan seaweed is often carried to the slopes of mountains to form humus to nourish trees.

The services rendered to agriculture by seaweeds are well known and very important. Buried in the earth, they are converted by fermentation into an excellent humus, of great service to plants, and the cultivators on the coasts of many countries carry away thousands of cartloads.

At Granville, in France, there is a large commerce in seaweed. The value of that used for manure cannot well be determined.

In France the collection of seaweed is only allowed at certain fixed periods, while in China and Japan it is carried on daily. Still, the former plan may have its advantages, as it is known that it is in the midst of this exuberant vegetation of marine plants many species of shell-fish, such as mussels, scallops, etc., live. It is also the spawning ground of a certain number of fish; and, finally, here the young fry and the crustacea find a shelter from the voracity of the large species of fish with sharp teeth, such as the congers, bonitos, etc.

The seaweeds form in the Atlantic considerable banks, especially in the part known as the Gulf Stream. There ships pass through large spaces entirely covered with them. Sometimes the banks take the form of long serpents, the two extremities of which cannot be seen. To these accumulations of plants the sailors give the name of Neptune's