PREPARATION OF INSTRUMENTS, ETC. 219 



twelve hours to remove lime deposits. Wash in running 

 warm water. Soak for fifteen minutes in a saturated solu- 

 tion of permanganate of potassium, then place in a satu- 

 rated solution of oxalic acid until they are perfectly bleached. 

 After immersion for half an hour in this solution rinse 

 thoroughly in sterile water and put in a i-iooo bichloride 

 of mercury solution for twenty-four hours. Remove and 

 place in 1-20 carbolic acid solution until required for use. 

 At operation remove from solution, rinse out in normal salt 

 solution, and place in receptacle filled with salt solution. If 

 sea sponges are used on a septic case they should be thrown 

 away and no attempt made to resterilize them. If used on 

 clean cases they may be resterilized as above. 



Dressings. The two materials universally used to dress 

 wounds are " gauze " or cheese-cloth and absorbent cotton. 

 If they are properly sterilized, the impregnation of gauze 

 or cotton with antiseptics does not* add to their value. 

 Gauze is usually cut in portions one yard square and folded 

 in pieces called compresses. A number of compresses are 

 wrapped with a piece of cotton cloth and the edges stitched 

 loosely into a closed bundle. After sterilization by the frac- 

 tional method, the bundles can be placed in sterile jars or 

 receptacles and each bundle removed as needed. Ripping 

 open the stitches gives untouched sterile bundles of com- 

 presses, convenient and handy for using. Cotton is sterilized 

 by the fractional method in rolls or bundles as for gauze. 

 These dressings should be warmed before being placed in 

 the steam sterilizer or they will be unnecessarily wet when 

 removed. 



Irrigating Solutions. Chemical germicides, such as bichlo- 

 ride of mercury when in solution, cause necrosis of tissue. 

 Plain sterile water causes maceration of epithelium. Nor- 

 mal salt solution is the least irritating to the tissues and is 

 the one most generally employed for irrigating purposes. It 



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