DISINFECTANTS AND DISINFECTION 333 



4. Indifferent antiseptics. 



Arsenious acid, 1-166 



Boric acid, 1-143 



Arsenite of soda, i-i i j 



Hydrate of chloral, 1-107 



Salicylate of soda, i-ioo 



Iron sulphate, i-po 



Caustic acid, 1-56 



5. Feeble antiseptics. 



Calcium chloride, 1-25 



Sodium borate, 1-14 



Alcohol, . i-io 



6. Very feeble antiseptics. 



Ammonium chloride, 1-9 



Potassium iodide, 1-7 



Sodium chloride, 1-6 



Glycerin, 1-4 



Ammonium sulphate, 1-4 



The following table gives the efficiency value of some disinfectants. 

 It will be seen that this value is of necessity variable, depending upon the 

 variation in the market price of the disinfectants. In will also be seen 

 that in the proposed rating the remarkably high coagulation coefficient of 

 some of the more important chemical disinfectants lowers the efficiency 

 value greatly. 



The efficiency value of any disinfectant is found by dividing the phenol 

 coefficient by the other coefficients as follows : 



Phenol coefficient Efficiency 



Tox. coefficient + Coag. coefficient + Comp. cost value 



In the table the first figure in the comparative cost column (4th column) is 

 the market price per pound of the disinfectant and the second figure is the 

 comparative cost (compared with phenol at 15 cents per pound). 1 



1 The comparative cost is a variable quantity. The present cost of phenol is much 

 higher than 15 cents per pound. The above figures would have to be revised to make 

 them applicable to the prevailing market price for the several disinfectants. 



