CONSTITUENTS OF PLANTS. 113 



crystals of salt, even at the distance of from 20 to 

 30 miles from the sea. But it does not require a 

 storm to cause the volatilization of the salt, for the 

 air hanging over the sea always contains enough of 

 this substance to make a solution of nitrate of 

 silver turbid, and every breeze must carry this 

 away. Now, as thousands of tons of sea-water 

 annually evaporate into the atmosphere, a corre- 

 sponding quantity of the salts dissolved in it, viz. 

 of common salt, chloride of potassium, magnesia, 

 and the remaining constituents of the sea-water will 

 be conveyed by wind to the land. 



This volatilization is a source of considerable loss 

 in salt-works, especially where the proportion of 

 salt in the water is not large. This has been com- 

 pletely proved at the salt-works of Nauheim, by 

 the very intelligent director of that establishment, 

 M. WUhelmi. He hung a plate of glass between two 

 evaporating houses, which were about 1200 paces 

 distant from each other, and found in the morning, 

 after the drying of the dew, that the glass was 

 covered with crystals of salt on one or the other 

 side, according to the direction of the wind. 



By the continual evaporation of the sea, its salts* 



* According to Mareet, sea-water contains in 1000 parts, 

 26'660 Chloride of Sodium. 

 4-660 Sulphate of Soda. 

 1 -232 Chloride of Potassium. 

 5-152 Chloride of Magnesium. 

 1-5 Sulphate of Lime. 



J 



