hold about a quart each, are tied up at the neck with flax fibre, and resemble in appearance a bottle of caoutchouc.

The large dried hollow fronds of a gigantic fucus serve as water buckets on the Pacific coasts of South America. Water pitchers used to be made by the aborigines of Tasmania of the broad-leaved kelp. They were often large enough to hold a quart or two of water. These and the shell of a species of Cymba were the only vessels they had for carrying water.

CHAPTER XIII.

MARINE SALT.

Mode of obtaining sea salt-Salines of France, where situated--Statistics of production-Composition of the crude salt-Manufacture in the United States-Consumption of salt in various countries-Sea-salt works of Portugal-Salt manufacture in India a Government monopoly-Imports of foreign salt-Salt production in Cochin China.

ANOTHER Commercial product from the sea is salt, obtained by evaporation, which is produced on a large scale in many quarters, especially in India, on the coast of France, in Turks Islands, and other localities. To obtain this salt a certain quantity of sea water is collected in reservoirs, constructed on the seacoast, which are termed salines, or salt marshes, where it is evaporated by the combined action of the rays of the sun and currents of air. As sea water contains only from two and a half to three per cent. of salt, a very large quantity of water has to be submitted to evaporation to obtain the salt of commerce. Notwithstanding this, the operations are carried on upon so large a scale, and the work is so arranged, that the salt is produced at a very moderate price.

France has about 82 salines, or salt marshes, occupying a surface of about 48,500 acres. These are situated, one

on the Channel coast, 36 on the shores of the ocean, and 45 on the coasts of the Mediterranean. These consist of one or more reservoirs, into which the sea water is passed. Those of the south are greatly superior to the others, because they are better managed, and the climate is more favourable for evaporation.

The sea water is introduced, either by means of a canal of the level of the sea banks, or by means of hydraulic machines in other cases, into a reservoir, which is shallow and of great extent of surface, so that the liquid may be subjected to the action of the sun's rays. In this reservoir, when the evaporation commences, the water passes off slowly into a series of rectangular basins, less deep, where it continues to concentrate, after which it passes into a trench which conducts it to the great wells, called the wells of green water. Pumps then raise it into a second trench, by which it is carried into another series of evaporating basins, called interior heaters, from which it passes into the reservoir, and from thence by a third trench into more wells, called the salt wells. Here the sea water marks 22° to 24° of Beaume's areometer. The pumps then pass it into a fourth trench, which carries it into new basins, smaller than the preceding ones, called salt tables. In these tables, where the liquid mass is not above five or six centimètres of depth, the salt is deposited. When the principal part of the water has left the product, the water is carried off by the canal to the sea, and a fresh quantity of condensed salt-water is brought into the salt-pans. The water is renewed daily or every two days, and this operation is carried on during all the fine weather, that is, from April to September. When the bed of salt is of the thickness of four or five centimètres, it is collected or shovelled up. For this purpose the masses of salt are left

to dry, and then collected with spades into long heaps or piles, which are called camelles. This operation is only carried on two or three times during the season. Finally, after long drainage, the heaped salt has parted with all its water, and is ready for passing into commerce.

The salt of the salines of the Mediterranean is in the form of very large and white crystals, and of a very fine purity. That of the salt marshes of the ocean is in the form of small grey crystals, and known in commerce as grey salt. It owes this colour to the earthy particles belonging to the basins, where it is collected daily.

To convert it into white salt it has either to be washed or refined, in order to remove the foreign substances which it contains. By the first process it is merely washed with water saturated with pure salt, after which it is drained and dried in stoves. By the second process, and by which very fine and white table salt is prepared, the grey salt is dissolved in ordinary water; the magnesia contained in the solution is precipitated with lime; it is then filtered and evaporated in shallow boilers.

The salt marshes worked in France are in the Bouchesdu-Rhône, and on the borders of the ocean, principally at the island of Ré, in the Landes, Charente-Inférieure, and Loire-Inférieure. As the production of the salt marshes is variable, the price of salt also fluctuates. The average may be taken at 2 francs per 100 kilogrammes, to which has to be added 12 francs duty, bringing up the price to 15 francs. According to the official statistics, the consumption of table salt in France in 1876 amounted to 301,328,000 kilogrammes, representing a value of 45,199,200 francs; and the exports were 1,862,000 quintals, value 3,000,000 francs, making the total commerce in salt, duty paid, amount to nearly £2,000,000 sterling, besides a good deal employed in agri

culture, the fisheries, and chemical industries, on which no duty is paid.

Marseilles is a great entrepôt for the trade in marine salt in France. In 1877 the deliveries were over 78,000 tons, of which 17,400 tons were exported, 39,000 tons locally consumed in the chemical and soap works, and 12,000 tons employed in the fisheries.

The following is the composition of the crude salt of the south and west of France :

The annual average production of marine salt in France in the ten years ending 1876 was as follows:

The quantity delivered for consumption, duty paid, was 315,549 tons; exported abroad, 109,633 tons; delivered free for various manufactures, 183,763; total, 608,945 tons. The tax on salt in France was raised to 12 francs the 100 kilogrammes by the law of the 2nd of June, 1875.

On some of the coasts of the Channel, marine salt is obtained by a process quite different from that adopted in the salines. During low tide the sand of the beach is collected, washed with sea water, which gives a very concentrated briny liquor, and this is evaporated to dryness