Marine Salt. 341 



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 be- 

 longing 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 Bouches- 

 du-Rh6ne, and on the borders of the ocean, principally at 

 the island of Re*, in the Landes, Charente-InfeYieure, and 

 Loire-InfeYieure. 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 1 5 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- 



