22 



Carbonic acid, as (Co 3) 0.000% 



Bicarbonic acid, as (HCO 3)2 0.164% 



Chlorine 1.162% 



Sulfuric acid (80 4) 0.119% 



Calcium , 0.090% 



Magnesium 0.031% 



Potassium 0.058% 



Sodium 0.683% 



2.307% 



The percentage composition of the incrustation as calculated from 

 this analysis, is as follows: 



/ 



Carbonic acid as (CO 3) 0.00% 



Bicarbonic acid (HCO 3)2 7.08% 



Chlorine 50.36% 



Sulfuric acid (SO 4) 5.17% 



Calcium 3.90% 



Magnesium 1.37% 



Potassium r 2.51% 



Sodium 29.59% 



100.00% 



It is readily seen that the main constituent of this incrustation, 

 commonly called "potasa" in that neighborhood, is sodium chloride, 

 which is mixed with small amounts of the bicarbonates and sulfates of 

 calcium, magnesium and potassium. 



Knowing the nature of the incrustation, it was desirable to find out, 

 in what quantities the salts found were present in the different parts 

 of the estate, and whether they are present to such an extent as to 

 influence the cane as regards growth, diseases and insects. 



Mr. Howells collected at each place a sample of the soil itself, and 

 besides a subsoil sample at the depth of five feet. Notes were taken on 

 the yield of the cane, the level of the ground water, the number of years 

 during which the field had been under cultivation, and on the use of 

 fertilizers. Mr. Shapley, Chemist of Plazuela, kindly furnished us with 

 analyses of the ground water at the different places wher<* 

 the samples were taken. The first of these was collected at the part 

 of the estate which is situated towards the Caiio de Tiburones, about 

 2800 meters west of the central factory, and the other samples at about 

 equidistant points in the direction towards the Central, that is east, and 

 then from there, at a right angle, going south, towards the hills. Table 

 VII gives the definite locations where the samples were collected, and 

 the other data obtained with the exception of the analyses of the gound 

 water which are given in table IX, (page 26). 



