CHAPTER XVII 



Care of Glassware 



USED slides are first separated from the cover slips; both are then 

 placed separately in 10 per cent solutions of cresol, which cleans and 

 sterilizes. After a few days they are rinsed in water and dried for use. The 

 same solutions of cresol may be used repeatedly. 



Discarded tubes of used mediums may be conveniently sterilized and 

 cleaned in the following manner. With the cotton pledgets in place, the 

 tubes are put in an upright position and left under a steam pressure of 

 15 lb. for one hour. All growth is thus destroyed. While the agar is still 

 liquid, the pledgets of cotton are removed and the tubes are filled with hot 

 water. The water dilutes the agar so it cannot again harden, and the con- 

 tents of the tubes now may be safely discarded into a drain without causing 

 trouble. The tubes require little more than a soaking in a solution of de- 

 tergent, such as Soilax, and a rinsing in clear water to be ready for use again. 

 With this teehnic, breakage is reduced. 



Petri dishes are best sterilized separately. After sterilization, as outlined 

 in the preceding paragraph, they are allowed to cool. The agar is then re- 

 moved with a spatula and the dishes are washed with soapy water or with 

 a solution of detergent. 



If anv tubes have been sealed with paraffin, cleaning them separately will 

 prevent the filming of other glassware. If wax pencil has been used to label 

 tubes or Petri dishes, it is preferable to remove the marks with benzene as 

 the dishes are discarded and before sterilizing. 



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