ARSENICAL DUSTING OF CABBAGE 



Table 1. — Analyses of arsenical materials used in experimental dusting of cabbage 

 at Charleston, S. C, and Baton Rouge, La. — Continued 





Lead ar- 

 senate, 1 at 

 Charleston, 

 experiments 

 1 to 4 



Calcium arsenate 



Constituents or properties 



At Charles- 

 ton, experi- 

 ments 5 

 and 6 



At Baton 

 Rouge, ex- 

 periments 

 1 to 6 





Percent 

 0.2 

 32.2 

 .0 

 .16 

 64.00 



Percent 



1.61 



38.95 



.25 



.11 



Percent 



1.10 





41.94 





. 12 





.10 









44.47 

 8.69 



47.28 







5.89 









1 Hypothetical composition: Di.'ead arsenate, PbHAsCh 

 percent. 



perceni; trilead arsenate, Pb3(As04)2, 



- The dusts were applied with rotary- type hand dusters by passing 

 over the row once when the plants were small, and twice at an angle 

 on each side, after the plants began to head. The applications for 

 each experiment were made at equal intervals unless weather or other 

 conditions interfered. 



In the Charleston experiments, the Charleston Wakefield variety 

 of cabbage was used exclusively. At Baton Rouge, the Copenhagen 

 Market variety was used in all of the experiments except nos. 3 and 5. 

 The Charleston Wakefield was used in experiment 3 and Stein Flat 

 Dutch in experiment 5. 



SAMPLING AND RESIDUE DETERMINATIONS 



The samples consisted of 10 heads taken at random from each 

 experiment, except for Charleston experiments 1 and 2, in which they 

 consisted of 20 plants. The plants were trimmed to conform to 

 United States grade No. 1 (allowing four loose wrapper leaves), 

 except in Charleston experiment 1, in which the entire plants, except 

 the stalk below the bottom. leaves, were analyzed. 



The arsenical residues were determined by following the method 

 recommended by the Association of Official Agricultural Chemists. 



In addition to the regular residue determinations, two special 

 analytical studies were made on samples of cabbage submitted from 

 the Charleston laboratory. The objective of these studies was two- 

 fold: (1) The determination of the number of cabbage plants required 

 for a reliable sample for arsenical-residue determination, and (2) the 

 determination of the normal arsenical content of untreated cabbage 

 grown in the Charleston area, and whether this was 'due to soil 

 contamination externally or to root absorption and normal plant 

 metabolism. 



In the first study it was found that an error as high as 20 percent 

 of the mean would permit a proper interpretation of the data and 

 that a sample of approximately 10 heads would be sufficient. In the 

 second study it was found that untreated cabbage grown in the 

 Charleston area normally contains approximately 0.0008 grain of 

 arsenic trioxide per pound in the compact inside leaves, and approxi- 

 mately 0.0017 grain in the outside loose leaves, one-third of the latter 

 resulting from external contamination. 



