66 BACTERIOLOGY 



cleansing suppurating wounds and loosening dressings 

 which have become adherent from dried secretions. It 

 should never be used in suppurating cavities where there 

 is not a free outlet for the gas which is formed by its 

 decomposition, as the pressure might force septic mate- 

 rial out into healthy tissue. 



lodoform. This is a yellow powder of high iodin con- 

 tent. It was formerly much used as an antiseptic in 

 dry dressings. It is in itself not antiseptic, and should 

 be sterilized before use on a sterile wound, but in con- 

 tact with pus it is decomposed, giving off free iodin, 

 which in turn acts as an antiseptic. Because of its 

 particularly obnoxious odor and slight germicidal value 

 it is rapidly falling into disuse. 



Aristol (Thymol lodid). This is a reddish-brown 

 powder containing 45 per cent, iodin. It has almost 

 supplanted iodoform as a dry dressing, being free from 

 its disagreeable odor and less toxic. 



Formidin. This is a reddish powder containing 

 formaldehyd, salicylic acid, and iodin in combination. 

 It is of greater value than either of the last-named drugs. 

 Being non-irritant and practically non-toxic, it may be 

 used both internally and externally without danger. 

 In the presence of wound secretions, pus, or the intestinal 

 secretions it breaks up into its component parts iodin, 

 formaldehyd, and salicylic acid all of which are anti- 

 septics. It is used as a dressing powder and for the 

 preparation of antiseptic gauze. 



