CHEMICAL DISINFECTANTS 139 



eucalyptoe, saturated with chlorine gas. It can be sprayed on a 

 surface or pressed into a wound. 



Carbolic acid is valuable as a disinfectant because of its stability. 

 A 1-1,000 solution inhibits bacterial growth; a 5 percent solution 

 is a thoroughly reliable disinfectant for morbid discharges; this 

 strength is not injurious to metals or fabrics. A thorough solu- 

 tion should be made, and to be very efficient, 5 percent HC1 

 should be added to it. 



Cresol, lysol and creolin are useful as disinfectants, but are 

 sometimes unreliable since perfect solution cannot always be 

 made. The mixture of one of these substances with water is 

 more of an emulsion than solution. Anthrax spores have been 

 known to live for hours in creolin solutions. The value of these 

 cresols is that when applied to a surface the water may evaporate 

 but the germicide sticks and continues its effects. Glycerine is 

 sometimes added to lighter phenol solutions to assist this action. 



Peroxide of Hydrogen has a great reputation in medicine as an 

 antiseptic. It kills bacteria, especially the pus cocci, in a few 

 minutes in a 15 percent solution. A 40 percent solution will kill 

 anthrax spores in a few hours. It is a powerful agent when fresh, 

 and is not poisonous. It combines with organic matter and 

 becomes inert. It degenerates if exposed to atmosphere and if it 

 comes in contact with the ferments of the blood (haemase). 



Formaldehyde gas, CH^O, is, by all means, the most useful, as 

 well as the most powerful disinfecting agent that we have. In 

 solution 40 percent in water, it is known as formaline. It has a 

 marked affinity for organic substances and forms chemical com- 

 binations with many organic bodies. When it unites with am- 

 monia it becomes inert until some acid frees it. It unites with 

 iron, but other metals are unaffected. Its use in medicine is wide 

 and varied. It is a deodorizer; renders gelatine glass-like and 

 insoluble in boiling water. It may be liberated as a gas in apart- 

 ments and ships, actively destroying all bacteria. One percent 

 of the vapor in the air of a closed room, if the air is moist, destroys 



