GLASSWARE FOR STERILIZATION 15 



pose a small quantity of some disinfectant (such as thy- 

 mol or camphor) which is without chemical action on the 

 constituents of the fluid is selected. 



An amount of carbolic acid (0.5%) or other chemical 

 is frequently added to vaccines, bac terms, serums, etc., for 

 preservative purposes. 



4. Disinfectants are sometimes used to sterilize a culture 

 when the products of the microorgansims are under inves- 

 tigation. Chloroform, ether, toluol, oil of garlic or mustard, 

 etc., which may be driven off afterward by evaporation, 

 are among the most useful in this connection. 



II. Sterilization by Antiseptics. Chemical reagents such 

 as belong to the class known as antiseptics, i.e., substances 

 which inhibit the growth of, but do not destroy bacterial 

 life, are obviously useless. 



REFERENCES 



EYRE: Bacteriological Technic. Second Edition (1913), pp. 26-48. 

 BESSON: Practical Bacteriology, Microbiology, and Serum Therapy 



(1913), pp. 3-27. 



MARSHALL: Microbiology (1911), pp. 64-67. 

 EULER: General Chemistry of the Enzymes (1912), pp. 118-123.. 



EXERCISE 2. PREPARATION OF GLASSWARE FOR 

 STERILIZATION 



The mouths of test tubes, fermentation tubes, pipettes, 

 etc., are ordinarily plugged with cotton before sterilization. 

 For this purpose cotton is ideal as it is cheap and adaptable, 

 serves to filter out microorganisms from the air, while allow- 

 ing the ready diffusion of gases, and after once used it may- 

 be burned. 



Paper (ordinary newspaper) may be used to wrap glass- 

 ware as Petri dishes, deep-culture dishes, pipettes, etc., which 

 one wishes to store in a sterile condition and for which 

 cotton is not adaptable. 



Glassware is sterilized for the purpose of destroying 



