102 



Journal of Agricultural Research 



Vol. XX, No. 2 



months, while a sample of eusol lost 10 per cent of its available chlorin in 

 24 hours. 



In view of the instability of eusol an attempt was made to secure a more 

 stable product by reducing the amount of boric acid, and it was found 

 that by reducing the proportions from equal parts of bleaching powder 

 and boric acid to 10 parts of bleaching powder and 3 parts of boric acid a 

 product was obtained which was fully as stable as Dakin's solution. This 

 modified eusol was tested by the carbolic-acid coefficient method in com- 

 parison with the regular eusol. The results are given in Table XV. 

 Eusol made by the original formula is designated as eusol I, while that 

 made by the modified formula is designated as eusol II. 



Table XV. — Carbolic-acid coefficients of eusol I {original formula) and eusol II {modified 

 formula), based on available chlorin 



Feb. 4. 



Do 

 Feb. 7. 



Do 



Solution. 



Eusol I. 

 Eusol II 

 Eusol I. 

 Eusol II 



Coefficient 



with 



Bacillus 



typhosus. 



Ill 



66.6 



100 

 66.6 



According to the results of these comparative tests it would seem that 

 eusol I is superior to eusol II in germicidal efficiency. 



INFLUENCE OF AMMONIA UPON THE GERMICIDAL EFFICIENCY OF 

 CHLORIN DISINFECTANTS 



It has been shown by Race (8) and Rideal (9) that the addition of 

 ammonia to electrolytic hypochlorite solutions greatly increases their 

 germicidal efficiency. Their explanation of this increase is that it is due 

 to the formation of chloramin (NH 2 C1). The experiments here discussed 

 were intended to verify these findings by the use of methods similar to 

 those employed in the experiments already discussed, without attempting 

 to ascertain the cause of the increased germicidal value. 



The method first used was the Rideal- Walker method (jo), modified 

 by the use of an unadjusted culture medium as recommended by the 

 American Public Health Association Committee on Standard Methods of 

 Examining Disinfectants (//). The method was also modified by deduc- 

 ing coefficients at times other than 7X minutes, and in many instances no 

 coefficient was obtained. 



By the use of this method experiments were first made upon Dakin's 

 solution, prepared from bleaching powder by the use of sodium carbonate 

 and bicarbonate as previously described. Ammonia was added so as to 

 furnish a molecular equivalent to the sodium hypochlorite of the Dakin's 

 solution. Experiment 26 (Table XVI) shows the comparative result s 

 with no organic matter added, and experiments 27 and 28 (Table XVI) 

 show the results with blood serum added. 



