DISINFECTANTS. 369 



blue solution formed when ammonia is added in 

 excess to a solution of copper sulphate. The usual 

 proportions are about 511). blue vitriol and 6 or 7 pints 

 of strong ammonia in 100 gallons of water. 



2. Ammoniacal copper carbonate, made by dissolving copper 



carbonate in ammonia or ammonium carbonate solu- 

 tion. Quantities often used are copper carbonate 

 10 ounces, strong ammonia 6 pints, water 100 gallons. 



3. Copper sulphate and sulphur powder. A mixture of equal 



weights of powdered blue vitriol and air-slaked lime is 

 mixed with 20 times its weight of powdered sulphur. 

 Copper sulphate and ammonio-copper sulphate also find a 

 limited application in veterinary practice as astringents. 



Copper sulphate is also used as a disinfectant in France, a 

 5% solution being recommended. It has been employed as a 

 disinfectant for cow-sheds after rinderpest, but is expensive. 



Disinfectants. A true disinfectant is a substance which 

 destroys the organisms (and their spores) which produce putre- 

 faction or disease. An antiseptic, on the other hand, is a 

 substance which prevents their growth, though it may or may 

 not destroy them. A deodoriser is a body which absorbs or 

 destroys the evil-smelling gases which are evolved during 

 processes of decay. 



Disinfectants act in various ways and it is impossible to 

 exactly correlate their germicidal action with their chemical 

 or physical properties. 



Eideal" classifies their action thus : 



1. Free acids or salts of acid reaction retard the growth of 



most bacteria. 



2. Albumen is precipitated by soluble salts of many heavy 



metals, e.g., mercury, copper, &c. Such salts pro- 

 bably act by coagulating the protoplasm in the 

 organisms. 



3. By combining with such metals, or in other ways, e.g., 



by contact with charcoal, the food of bacteria may 

 be rendered insoluble and the organisms are thus 

 starved. 



* Disinfection and Disinfectants, 1895, 145. 



BB 



