DENSITY 31 



their character and quantity according to the soil and rock strata through 

 which the water has passed. Such water ultimately finds its way to the 

 sea, and there again undergoes evaporation, leaving the solids behind either 



n 



Fig. 16. 



dissolved or deposited, so that the sea is the liquid residue of ages of evapo- 

 ration. The action of rain water as a solvent on soil may be illustrated b> 

 percolating soil with rain water in the apparatus figured, and comparing the 

 residues of evaporation of the rain and drainage water. 



VIII. DENSITY 



It is well known that salt water is more buoyant than pure 

 water. This is owing to its greater density. Compare the 

 densities of water and a saturated solution of salt by com- 

 paring the weights of equal volumes of the liquids. Run 

 20 C.C. of the salt solution from a burette into a small 



