Marine Salt. 345 



lime salts. Finally, it is led into basins where it begins to 

 deposit the salt, the water in these compartments being 

 only a few inches in depth. When the land is sufficiently 

 below the level of the sea to allow the water to flow from 

 one set of basins into the adjoining ones, of course the pro- 

 cess is rendered quite easy ; but if it is not low enough, 

 the brine is raised at various stages by pumps moved by 

 windmills. Salt produced in this way is called bay salt, 

 and can only be made in very dry countries, as a few hours' 

 rain would spoil the labour of weeks. When wooden tanks 

 are used, they are generally protected from the rain by 

 coverings. The tanks are made about ten feet square, and 

 a foot deep. The roofs are moved off and on by the aid of 

 wheels running on rails, or, what is more common, two roofs 

 are fastened together by their corners, and so arranged 

 that they will turn about on a pivot, covering or uncovering 

 two tanks by one movement. 



The average consumption of salt per head in various 

 countries has been roughly estimated to be as follows : — 



No marine salt is made in the United Kingdom, but 

 the manufacture of salt reaches about 1,500,000 tons, nearly 

 half of which is exported, chiefly to India and the United 

 States. 



Sea salt is made to a small extent in Algoa Bay and 

 other parts of the Cape Colony, and in Australia. 



The sea-salt works of Portugal are very extensive, and 

 produce annually 250,000 tons of salt, which is in great 

 request. The centres of the manufacture are Setubal, 



