330 



Journal of Agricultural Research 



Vol. XII. No. 6 



Table IV. — Analyses of dilute and average solutions by the methods used in this 



investigation 



The determinations on each element are given on six duplicate portions 

 of solution. In addition, the mean percentage of error is calculated, as 

 well as the maximum error for any single determination. It will be ob- 

 served that the agreement with the theoretical result is satisfactory for 

 such dilute solutions. The potassium determination shows the greatest 

 discrepancy, with a mean error of 10 per cent and a maximum of 19 per 

 cent on the dilute solution. On the average solution the results are 

 much closer, ranging from 3.6 to 10 per cent. With calcium the error 

 on both the dilute and average solution is even smaller, 4.0 and 3.0 per 

 cent for a mean result, and 10 and 5.4 per cent for a maximum. The 

 phosphate determination shows a slightly larger fluctuation; in the 

 dilute solution from 6 to 20 per cent, but the higher figure was only 

 obtained in one analysis. The stronger solution gave greater accuracy 

 than was obtained in any of the other work. 



Taken as a whole, it is believed that the number of determinations is 

 sufficiently large to show the small probability of the occurrence of the 

 maximum error. The mean error will therefore be taken as the usual 

 figure to be applied in the interpretation of the subsequent results. 

 All data bearing on the seasonal studies which follow will be considered 

 in the light of their accuracy as affected by the mean and maximum 

 error. 



