33 



WATER SOLUBLE CONSTITUENTS. 



Carbonates 0.000% 



Bicarbonates, (HCO 3) 2 0.112 " 



Chlorine, CI 2 0.084" 



Sulfates, (SO 4) 0.114" 



The formation of this incrustation is easily explained. As the soil 

 contains a large percentage of calcium carbonate, considerable quantities 

 are dissolved during wet weather, by the combined action of water and 

 of the carbon dioxide dissolved in it. In dry weather this solution cf 

 calcium bicarbonate rises to the surface and dries up, losing a part of it>s 

 carbonic acid, and being redeposited as normal calcium carbonate. 

 Naturally, chlorides and sulfates are mixed with it, having risen to the 

 surface through the same forces as the calcium bicarbonate. 



It is important to note that in the incrustation of the first type, the 

 sulfuric acid radicle, S04, amounts to less than 9% of the total water 

 soluble acid radicles, whereas in that of the second type its quantity is 

 37% of the total. Again, in the different soil samples of the first series, 

 the same relation ranges from 6 to 9%, and in those of the second from 

 21 to as much as 78%, as Ave shall see from the analyses given further 

 on. 



Having pointed out these important differences in the characteristics 

 of the areas investigated, we shall now examine in detail the results of 

 the study of the Tiburones swamp lands. 



As before, we shall again give the results of the field investigations 

 in tabular form. We have stated above that the samples were taken along 

 a cross section of the swamp, at a right angle with its longitudinal axis, 

 beginning at the north border of the swamp and proceeding south to 

 its south border. Towards the two sides the land is higher than towards 

 the center of the marsh, as may be judged from the water levels given in 

 table XII. Column 1 of this indicates the distance of each location from 

 the edge of the field lying next to the north border of the swamp ; column 

 2 gives the height of the water level, and column 3 the condition of the 

 cane growing at the point where the sample was taken. 



