HALE TOXICITY COEFFICIENT 175 
or any other equal proportion of stock solution and distilled water may 
be used, as 5+0.5, 100+10, or 1000+100, ete. 
If the highest stock dilution (1/100,000) is to be used, then the 
increase should be by 10,000, thus: 
10+1=1/110,000 
10-+2=1/120,000 
10+3=1/130,000, ete. 
DETERMINATION OF THE PHENOL COEFFICIENT 
Having determined that dilution which gives the same coagulation 
opacity as the 5 per cent carbolic acid, it is a very simple matter to 
determine the phenol albumen coagulating coefficient by simply dividing 
the strength of the dilution of the disinfectant tested by the phenol 
dilution (1/20). 
We conclude by giving the coagulating coefficients of a few disin- 
fectants: 
Name of Disinfectant. Reaction C Ehenol | 
Phenol .. ......... eden e teen cee e ee eseeeneeeeee 1/20 1.00 
Copper sulphate. ..........0 cece cece cece cee ececes 1/15,000 750.00 
Mercuric chloride........... 2.0 c eee eee eee eens 1/10,000 500.00 
Silver nitrate 2... cece cee cece tee eee eens 1/9,500 475.00 
Alcohol 20.0 oc ccc ccc cee cece weet eet eee eens 1/3 0.15 
The Hale Toxicity Coefficient of Disinfectants. Hale has attempted 
in this procedure to establish the toxicity of different substances and to 
give them a definite numerical relation to other toxic agents. He 
further proposed that this toxicity coefficient be established for groups 
of substances having, in general, a similar pharmacological action. 
The following procedure was proposed for determining the toxicity 
coefficient of phenol-like compounds: 
The animal upon which the substance in question is to be tested 
shall be the white mouse of not less than 15 nor more than 30 gms. 
weight. The dose is to be calculated per gram of body weight and 
should, when diluted, equal between 0.03 and 0.04 c.c. per gram weight; 
that is, 0.06 to 0.08 c.c. for a 20-gm. mouse. The diluent is to be dis- 
