EVAPORATION OF SALINE WATER 



473 



Another illustration of the ability of salt in solution to escape from 

 any open containing vessel in which it may be placed is furnished by a 

 second experiment which was designed originally to elucidate another 

 subject. A tube was used in which clay and sandy materials were depos- 

 ited from a saline solution. A bit 



of pine stick was left standing in 

 the top of the tube until the water 

 had completely evaporated. It was 

 then observed that the salt had also 

 entirely left the tube, so far as the 

 eye could detect, and formed an in- 

 crustation about the upper part of 

 the stick. Although the surface of 

 the salt water containing suspended 

 clay was never higher than one 

 inch below the top of the tube, the 

 salt as the water evaporated formed 

 an incrustation which extended 

 nearly an inch above the original 

 surface of the water. In another 

 experiment an open fruit jar was 

 partly filled with saline water 

 which was allowed to evaporate 

 slowly. The supply was renewed 

 from time to time till the upward 

 creeping salt had entirely closed 

 the mouth of the jar and formed 

 a considerable mass above it, as 

 seen in figure 2. The dome which 

 completely closed the top of this 

 jar was found to have a maximum 

 thickness of about II/2 inches, but 

 showed no crystals. The bottom 

 of the jar was covered to a depth 

 of about one-half inch with salt 

 crystals from one-sixteenth to one- 

 eighth inch thick. 



These examples illustrate a process which must be continually in prog- 

 ress on the seacoast, particularly in dry climates, through which on rocky 

 shores large quantities of salt are separated from the sea-water and be- 

 come subject to the action of the wind. Such incrustations would be 



Figure 2. — Salt Efflorescence 



The glass jar was kept partially filled with 

 a saline solution until the ascendiag salt had 

 completely closed the mouth and coated the 

 outside. X Mj 



