CHEMICAL DISINFECTANTS 123 



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

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

 kills spores in a few hours. A thorough solution 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 germi- 

 cide sticks and continues its effects. Glycerin 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 2 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 combi- 

 nations with many organic bodies. When it unites with ammonia 

 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 apartments and ships, 

 actively destroying all bacteria. One percent of the vapor in the 

 air of a closed room, if the air is moist, destroys bacteria after 

 twelve hours. It is best to keep the room closed for twenty-four 

 hours. It may be thrown into the room in many ways ; by genera- 

 tors which decompose the vapor of wood alcohol, when they 

 reach hot platinum sponges, salt, or hot copper; by vaporizing a 



