14 BULLETIN 989, U. S. DEPARTMENT OF AGRICULTURE. 



the year from. 1.45 to 3.23. The greatest individual drop in one year 

 was from 1.71 when freshly made to 1.45 at the end of the year. 

 The average was 2.47 when freshly prepared, 2.52 at the end of 

 the month, and 2.46 at the end of the year. No deterioration could 

 be demonstrated. It should be noted that these samples varied one 

 from the other more markedly than did the Hygienic Laboratory 

 pine-oil disinfectants, one showing a coefficient of 1.71, another a 

 coefficient of 3.42. 



Two samples of the wood naphtha oil emulsion were examined. 

 One gave a coefficient of 0.70 when freshly prepared, 0.60 at the 

 end of a month, and 0.60 at the end of a year. The other gave a 

 coefficient of between 0.54 and 0.60 when fresh. 0.44 at the end of 

 a month, and 0.45 at the end of a year. The slight decrease in the 

 coefficient noted at the end of the first month is too small to indicate 

 any definite deterioration. 



A sample of " light " crude-oil emulsion gave a coefficient of 0.85 

 when fresh, 0.75 at the end of a month, and 0.90 at the end of the 

 year. A second sample, examined within a month of its manufac- 

 ture, showed a coefficient of 0.84. At the end of the year the coeffi- 

 cient was 1.03. 



A sample of the "heavy" crude-oil emulsion had a coefficient of 

 0.74 when examined in the first month. At the end of a j T ear it 

 was 0.78. ' 



A sample of emulsion made from the entire crude oil gave a coeffi- 

 cient of 0.60 when fresh, 0.64 at the end of the month, and 0.64 at 

 the end of the year. A second sample gave a coefficient of 0.74 at 

 the end of a month, and 0.85 at the end of the year. 



Two samples of tar-oil emulsions showed coefficients of 0.82 and 

 0.70 in the first month, and 0.84 and 0.83, respectively, at the end of 

 a year. 



The action of these samples on M. aureus and B. anthracis was 

 similar to that of the Hygienic Laboratory pine-oil disinfectant. 

 That is to say, when tested against M. aureus strain 200, they gave 

 Rideal-Walker coefficients ranging from none to 0.7, but when tested 

 against strains 202 and 203, they failed to kill in any dilution. Like- 

 wise they failed to kill B. anthracis in 5 and 10 per cent emulsions. 



CONCLUSIONS. 



Pine-oil emulsions made from steam-distilled pine oils, when 

 freshly prepared, gave Hygienic Laboratory coefficients varying from 

 3.42 to 4.34, the average being 3.88. At the end of 12 months the 

 average was 3.66. 



A. disinfectant prepared from destructive-distilled pine oil is 

 weaker as well as more variable in its germicidal power against B. 

 typhosus than is the Hygienic Laboratory pine-oil disinfectant. The 



