KELP. A common term for sea-weed or vraie, which consists of different spe cies of Focus (varec). In a strict sense, the term kelp is confined to the produce of sea-weeds when burned, which con sists of alkaline ashes used in the manu facture of glass and soap. It has been recently found, however, that the alkali required for these purposes can be ob tained more abundantly from sea-salt, and kelp is at present chiefly used as a manure. For this purpose it is eagerly sought after by all farmers on the sea coast, and especially by those who have dry soils, the salt contained in the kelp being a powerful absorbent of moisture from the atmosphere. It has lately quired much importance as a source of The species used in the manufacture of this article grow to rocks, between high and low water mark. On the Scottish coast it is cut close to the rocks, during the summer season, and spread, and turned to dry. It is then stacked and sheltered, till covered with white saline efflorescence, and is then ready for burning, in a round pit or kiln, lined with brick. or stone, about 2 ft. wide, 8 to 18 long, and from 2 to 3 deep. The bottom is covered with brush, upon which a little dried sea-weed is scatter: ed, and fire is applied at one extremity ; the sea-weed is now thrown on gradu ally, as fast as the combustion reaches the surface. After the whole is burnt, the mass gradually softens, beginning at the sides, when it should be slowly stir red up with a heated iron bar, and in corporated till it acquires a semi-fluid consistence. This part of the process re quires considerable dexterity ; and, if the mass continues dry, a little common salt should be thrown on it as a flux. When cold it is broken up, and is ready for sale.
Kelp contains but 2 or 3 per cent. of carbonate of soda, while Spanish barilla often contains 20 or 30. One of the pro ducts is iodine.
The use of soda, in general, is the same with that of potash, but it is indispensa ble in making plate and ground glass and hard soaps, and consumed in immense quantities by soap-boilers, bleachers, and It is well known that the shores of the sea, and salt-marshes, as well as the margins of interior salt-lakes and sa lines, and, in general, all places to which water holding salt gains access, are in habited by peculiar plants. In these
maritime plants, soda replaces the pot ash, which is always present in plants growing in ordinary situations, and if they are removed to a distance from the sea-shore, they gradually lose their soda, and acquire potash in its stead. The barilla obtained in France from the sali cornia amnia yields 14 or 15 per cent. of soda.
The Highland Society of Scotland has published the following account of the manufacture of 115 tons of kelp in Harris. It was from cut-ware of two years' growth, in equal parts of lady-ware, which grows between the spring and neap high tides ; bell-ware, between high and low neap tides ; black-ware, low water, spring and neap. It is cut with a strong reaping book. Sand and mud is washed oft, and it is spread by day, and cocked by night. Thenput into large cocks, and left to heat for six or eight days. It is burnt on a dry day, and a good breeze. The kilns are of hard stones, with turf out side, from 15 to 18 feet long, 21 ft. broad and 2 feet high. Straw or heather is laid over this, set on fire, and dry-ware added on the top by degrees till the whole is in ashes. If it cakes, it must be raked. When all is burned, it has the appear ance of a semi-vitrified solid. It is then broken into large lumps, and kept cover ed until it is put up in the cask for ship ment. The following two analyses of kelp, one from Cherbourg, made by Gi rardin, and the other from Spain, made by Richardson, show it to be made up mainly of sulphate and chloride of potas sium, and chloride of sodium, or common salt.
Cherbourg Spain.
Sulphate potash 42.54 10•85 Chloride potassium 1964 10.55 Chloride sodium 25-38 6835 Carbonate of sqda 311 traces Sulphate lime 11.0 Insoluble matter Iodine compounds traces ....
Water 8• COO - -- 100-00