GENERAL BACTERIOLOGY 
41 
and multiplication—such substances are spoken of as 
“antiseptics.” 
I. Bacterial Destruction by Physical Agents 
1. Drying.— When complete drying destroys most of 
the pathogenic bacteria, but the individual bacteria dif¬ 
fer greatly from each other in this respect; thus, 
gonococcus and the bacillus of influenza are destroyed 
within a few hours, while the tubercle bacillus may live 
without a trace of moisture for months. 
2. Light. —Sunlight is a powerful germicide (from 
Latin meaning life killing), the different bacteria vary¬ 
ing from each other in this respect also, the tubercle 
bacillus dying within two hours; for this reason “where 
there is sunlight there is no tuberculosis.” 
3. Electricity, Radium and Roentgen Rays.—See the 
preceding chapter. Briefly stated, x-rays have no in¬ 
fluence, while the electricity and radium are both 
germicidal. 
4. Heat.—This is the standard and universal method 
of bacterial destruction. 
Dry Heat.— Burning, when we are dealing with ob¬ 
jects without value, such as, e. g., the sputum cups, is 
a very rapid and a sure means of sterilization. Hot air 
sterilization is carried out in the so-called “hot-air 
chambers” or sterilizers. (Fig. 5.) This is a double- 
walled, sheet-iron chamber, with the joints riveted in¬ 
stead of being soldered. The inner case is completely 
closed, while the outer one has a large opening in the 
bottom and two small ones at the top; the gas burners 
—one on each side—are so placed between the two 
walls that the flame plays directly on the inner case. 
This method of sterilization is used primarily for the 
glassware, and the temperature should be between 150° 
