Marine plants afford a large revenue for the manufacture of kelp and iodine. Kelp is prepared by burning the dead weeds till they are reduced to hard, dark-coloured cakes, in which state it is sent to market. Kelp is the only commercial source for the production of iodine, and its immense value in photography and in medicine has given an impulse to the manufacture of kelp, which renders it by far the most important of all the applications of seaweed. The average yield of iodine in Scotland from a ton of driftweed kelp is about five pounds.

The proportion of iodine in sea water appears to be very small, and it would require more than 30,000,000 pounds of sea water to furnish the marine alga with one pound of iodine.

The production of kelp in the United Kingdom amounts to about 10,000 or 11,000 tons; the manufacture is carried on in Ireland, the Western Islands, and Orkney and Shetland. In France there are many large factories at Granville, Cherbourg, etc.

The manufacture of iodine is chiefly confined to Great Britain and France, for very little is produced in any other countries. It was attempted on the American coasts of the Atlantic, but the weed was found to be of too poor a quality. The average production of iodine is about 10 lbs. to the ton of kelp, and as it requires 20 tons of wet weed to produce one ton of kelp, the total quantity made represents the burning of 400,000 tons of seaweed annually. At the present price the iodine produced is of more value than the alkaline salts, which were the original object of the industry.

Carrageen Moss.-One of the best known of the alga in commerce is the Chondrus crispus, the source of carrageen or Irish moss, which is sometimes employed as a substi

tute for size and in brewing. It possesses nutritive, emollient, and demulcent properties, and may be employed in the form of a decoction or jelly in pulmonary complaints and other cases. Bandoline or fixature, for stiffening the hair and other purposes, is commonly prepared from carrageen. The market supply for England is obtained from Clare and the west coast of Ireland. It used to be sent to the United States, where it is kept on sale by FIG. 25.

1. Ulva latissima (green sloke). 2. Chondrus crispus (carrageen moss). most druggists. But it was soon found growing in immeasurable abundance along the whole Atlantic coast, from Nova Scotia to Long Island.

Comparatively few are aware of its wide and varied use in the arts, or of the thousands of barrels of it employed annually by manufacturers of paper, cloth, felt and straw hats, etc., and by brewers. Carrageen is to be found more or less abundantly all along the North Atlantic

coast, ranging between low-water line and the depth of 40 feet or so; but as a rule its fronds, which correspond to the leaves of air plants, are so numerously inhabited by small mollusca that they are spoiled for other use. The clean-growing article seems to be limited almost wholly to certain ledges in the neighbourhood of Scituate, Massachusetts. Here, where the waves of the Atlantic dash with full force upon the rocky coast, the carrageen grows to perfection; and, wherever it escapes the spawn of mussels and other shell-fish, is gathered during the summer season in vast quantities. The harvest begins in May and ends about the Ist of September.

The gathering is made in two ways-by hand-picking during exceptionally low tides, and by means of longhandled iron-toothed rakes at ordinary tides. Of course the work cannot be carried on except in fair weather. Hand-pulling is possible only during the bi-monthly periods of spring tides, that is, when the moon is full and again at new moon. At such times high tides occur about midday and midnight, and the ledges are exposed for moss gathering morning and evening. The mossers' boats are rowed to the rocks where the finest grades abound, and the gatherers select with care the growths that are freest from minute shells and other foreign matter. This portion of the crop, if properly handled afterwards, generally goes to the apothecary, and fetches a price two or three times that of the common grade. As the tide rises the pickers are driven to their boats, and proceed to the outer mossbearing rocks, where the rake is used, as it also is during ordinary low tides. Moss taken in this way is not so clean as the hand-picked, and is always mixed with tape grass, which must be removed during the process of curing and packing.

The preparation is the most critical part of this peculiar farming. On being brought to the shore the moss is black and unsightly; it must be bleached as well as dried. The bleaching is effected by repeated wetting and drying in the sun; and, as the moss is readily soluble in fresh water, the bleaching beds are situated near the banks of the salt creeks that abound along the shore. After drying, the moss is packed in tubs and rolled to the water, where it is thoroughly washed, then rolled back to the bleaching bed, to be dried again in the sun. Five or six such exposures are usually sufficient. On the bleaching ground the moss is carefully spread and turned, and watchfully guarded against wetting by rain. In this process it changes from black to red, then to the yellowish-white of the perfected article. When properly cured the moss is stored in bulk, in shanties, where, as time permits, it is picked over and packed in barrels. The crop averages about 500,000 lbs. a year; and, owing to the brighter and more abundant sunshine of the American coast, the moss has a better colour and is of finer quality than the Irish product.

The principal useful seaweeds occurring on the United States coast are the following:

For Food.-Chondrus crispus, Lyngb., commonly called Irish moss. It is abundant on the New England coast, particularly to the north of Cape Cod, growing just below water mark. It is gathered in large quantities at Hingham, Massachusetts, and sold for making blancmange, puddings, and sea-moss farina. It is also used by brewers for clarifying, and by calico-printers.

Scherzymenia edulis, Grev. Common dulse, sold roughdried in the seaport towns of the Northern States; principally eaten by sailors and children. That found in the American markets is generally imported from the British

Y

Provinces, although the plant is very common in New England.

Porphyra vulgaris, Ag. Laver; eaten stewed in some parts of Europe. It is imported from China by the Chinese living in the United States, and even by those as far east as Massachusetts, although the plant is common on the Massachusetts shore.

Alaria esculenta, Grev. Common on the New England coast north of Cape Cod. It is eaten in Scotland, but not in the United States. No doubt, Euchemia spiniforme of Key West, Gigartina mammilosa (often gathered by mistake for the true Irish moss), the Californian species of Chondrus, and some of the species of Gracilaria are quite as good for culinary purposes as the Irish moss.

Other Uses.-The sea-lettuce (Ulva latissima, L.) is used by owners of aquaria for feeding some of the marine animals, particularly mollusca.

Many of the seaweeds are used as fertilizers. The larger dark-coloured seaweeds are roughly distinguished by the inhabitants of the shore as rock-weeds, or those furnished with small bladders or snappers, and kelp. The rock-weed of New England is composed almost entirely of three species of Fucus-F. vesiculosus, F. nodosus, and F. furcatus. The kelp of New England is composed of the devil's aprons, species of Laminaria, the sea-colander, Agarum turneri, and Alaria esculenta. The rock-weeds and kelp are all useful for manure, and are either scattered over the land and allowed to rot, or else manufactured, together with other substances, into marketable fertilizers.

The red seaweed (Polysiphonia Harveyi) is said at times to be washed ashore in Peconic Bay in such quantities that it is used as manure.

The great kelp of California (Macrocystus pyrifera)