Earth Study 827 



SALT 

 Teacher's Story 



A "saturated solution" is an uninspiring term to one fv^^"^^^^ 

 not chemically trained; and yet it merely means water ' ^**" 

 which holds as much as it can take of the dissolved sub- 

 stance; if the water is hot, it disso' ves more of most sub- 

 stances. To make a saturated solution of salt we need two 

 parts of salt or a httle more, for good measure, to five parts Fo''^ "f "■ ^«^^ 

 of water; the water should be stirred until it will take up crystal. 



no more salt. 



A slip of paper placed in a saucer of this solution will prove a resting 

 place for the crystals as they form. In about two days the miracle will be 

 working, and the pupils should now and then observe its progress. Those 

 saucers set in a draft or in a warm place will show crystals sooner than 

 others, but the crystals will be smaller; for the faster a crystal grows, the 

 smaller is its stature. If the water evaporates rapidly, the crystals are 

 smaller, because so many crystals are started which do not have material 

 for large growth. When the water is evaporated, to appreciate the beauty 

 o i the crystals we should look at them with a lens or microscope. Each 

 crystal is a beautiful little cube, often with a pyramid-shaped depression in 

 each face or side. After the pupils have seen these crystals, the story of 

 where salt is found should be told them. 



Salt is obtained by two methods: by mining large deposits of rock salt, 

 and by evaporating water containing a strong solution of salt. The oldest 

 salt works in this country are in Syracuse, New York, where the salt comes 

 from salt springs which were famous among the American Indians. At 

 Ithaca, N. Y., the salt deposits are about 2000 feet below the surface of the 

 earth. Water is forced down into the stratum of rock, which was evidently 

 once the bottom of a briny sea; the water dissolves the salt, and it is then 

 pumped up to the surface and evaporated, leaving the salt in crystals. In 

 Michigan and Louisiana there are other large salt works of a similar 

 character. The largest salt mines in the world are those in Poland, which 

 have been used for hundreds of years. In these mines there are fifty miles 

 of corridors, and the salt has been carved into beautiful chambers with 

 statues and other decorations, all cut from the solid salt. One of these 

 chambers represents a chapel beautifully ornamented. 



When the United States was first settled, salt was brought over from 

 England; but this was so expensive that people could not afford it and 

 they soon began to make their own salt by evaporating sea water in kettles 

 on the beach. In those countries where it is scarce, salt is said to be literally 

 worth its weight in gold. The necessity for salt to preserve the health of 

 both people and animals has tempted the governments of some countries to 

 place a special tax upon it; in Italy, especially, the poor people suffer 

 greatly on account of the high price of salt from this cause. 



Salt lakes are found in natural basins of arid lands, and are always with- 

 out outlets. The water which runs in escapes by evaporation, but the salt 

 it brings cannot escape, and accumulates. A salt lick is a place where salt 

 is found on the surface of the earth, usually near a salt spring. Animals 

 will travel a long distance to visit a salt lick which gained its name through 

 their attentions. 



