2 LABORATORY BACTERIOLOGY 



tory). After it has acted for from lo to 20 minutes, pour it out 

 of the tubes into the bottle originally containing it. Rinse the 

 tubes thoroughly in running tap water until all color disappears, 

 and then in hot water, and drain them, using individual drain- 

 age board from locker. After they are dry, wipe the outside 

 of the tubes with a slightly dampened cloth. 



(d) Fermentation tubes. Treat these in the same' manner 

 as the test tubes, excepting in the use of the brush, which must 

 be omitted. 



(c) Flasks. Wash the flasks thoroughly with soap and 

 water. Then fill them with the cleaning mixture and allow 

 it to act for at least 10 minutes, after which it is to be poured 

 back. Rinse the flasks thoroughly in the same manner as the 

 test tubes and drain them. When dry, the outside should be 

 wiped with a damp cloth. 



(d) Petri dishes and reagent bottles. Thoroughly wash the 

 Petri dishes and reagent bottles in hot soap-suds, after which 

 rinse them separately in hot water. Wipe the Petri dishes dry 

 with a soft cloth and drain the bottles. The cleaning mixture 

 need not be used. 



(^) Cover-glasses and slides. Drop the cover-glasses singly 

 into a glass jar containing cleaning mixture and allow them to 

 remain there for 24 hours or longer. Pour off' the cleaning 

 mixture and rinse the cover-glasses in boiled water until all of 

 the color disappears, then cover them with alcohol until needed, 

 when they can be wiped with a soft linen cloth or with lens 

 paper. After they are wiped out of the alcohol, place them in 

 a Petri dish without the cover, and heat them in the dry air 

 sterilizer at a temperature of 160-180° C. for one hour. 



After they have cooled, replace the cover and allow the cover- 

 glasses to remain in the Petri dish (a glass jar or other closed 

 dish may be used) until used. (When a drop of water or bouil- 



stant stirring, to 460 c.c. of concentrated sulphuric acid. Store the riiixture in 

 a glass-stoppered bottle. The liquid will be quite thiclt with small crystals. 

 When the crystals are used up, the liquid should be discarded. 



