OXIDATION OF AKSENIC IX DIPPING BATHS. 



9 



hare two fully developed opposing forces in the vat — one tending to 

 oxidize the arsenic, the other to reduce it. Which agency will gain 

 the ascendency at any given time will depend chiefly on the quantity 

 and frequency with which cattle are being put through the bath. 

 Frequent and abundant use of a bath will favor reduction; limited 

 and infrequent use will favor, oxidation. The oxidizing organisms 

 must be conceived as working slowly but steadily and persistently 

 under all conditions of use; the reducing organisms may work very 

 rapidly when they work at all, -but they work only spasmodically 

 during ordinarily brief periods when the bath happens to be suffi- 

 ciently rich in nutrient matter. 



The next series of experiments were upon the effectiveness of cer- 

 tain antiseptics against the activity of both reducing and oxidizing 

 organisms, with the double purpose of rinding (1) a reliable means 

 for preserving samples for analysis after removal from the vat and 

 (2) a practical means of preserving the bath in the vat. 



Experiment 4- — To determine if a layer of oil floated over the sur- 

 face of the bath during periods of disuse would prevent oxidation. 

 Mixture made in the usual way, placed in beakers, and covered with 

 layers of oil of approximate thicknesses noted below. 



Table 4. — Effect on oxidation of oil floated over surface of bath. 



No. of test 



a (no oil) 



b (1 mm. paraffin oil).. 

 c (0.1 mm. paraffin oil) 



d (no oil) 



e (1 mm. kerosene) 



Per cent actual AS2O3 by 

 analysis. 



Original. 6 days. 10 days 



0. 255 

 .255 

 .255 

 .194 

 .194 



0.185 

 .219 

 .204 



0.003 

 .219 

 .009 

 .013 

 .033 



Experiment 5. — On the efficacy of cresylic acid as an antiseptic 

 against oxidation. Mixtures made in the usual way, certain pro- 

 portions of cresol being added in the form of liquor cresolis compositus, 

 U. S. P. 



Table 5. Kfftrt of rrryj/lic a< id as an arilisc/il ic aaainst oxidation. 



No. <>f leet. 



Per cent actual AS2O3 by 

 analysis. 



Original. 



a 'nw resol) 



pei ccnl ere ol) 

 per cenl ere ol) 

 <i <"o. 10 jntr cenl ere of) 

 e i<)..',i) percent cresol). 



0.201 

 .201 

 .201 

 .201 

 .203 



li ilaj :. 



0. 027 

 . H)li 

 .146 

 . 1 83 

 . 185 



10 days. 



0.006 



. 003 



. 180 

 . L81 



