170 Microbes and You 



rays are true electromagnetic waves similar to X rays but of a 

 shorter wavelength. They have great penetrating power but their 

 destructive action on bacteria is apparently very slight or nil. The 

 present state of our knowledge indicates that bacteria may be 

 affected by alpha and by beta rays, but the lethal action appears 

 to be slight, at best. 



ELECTRICITY 



The harmful effect of electricity on bacteria apparently is a 

 combination of a heat reaction and liberation of ozone, nascent 

 oxygen, or chlorine from the bacterial substrate. Attempts to treat 

 water with the use of electric currents has been shown to be too 

 expensive in some localities, to say nothing of some of the technical 

 difficulties involved. But pasteurization of milk using the electro- 

 pure process is a common practice that is growing in popularity. 



In some localities where electric power is reasonable, sewage 

 may be freed of harmful organisms by passing 2.5 volts of elec- 

 tricity through the effluent. Chlorine gas appears at one electrode 

 and alkalies appear at the other electrode, and the process is 

 feasible. 



CATHODE RAYS 



These rays may be generated by Coolidge electron tubes and 

 have been found to be destructive to bacteria, but too limited 

 investigation has been carried out to date to make any further 

 claims for these cathode rays. 



ULTRASOUND 



The word supersonic, to a physicist, means frequency in cycles 

 per second of sound waves pitched too high to be audible to the 

 human ear. Ultrasonic, on the other hand, is anything beyond 

 the speed of audible sound, which is about 760 miles an hour at sea 

 level. 



Sonic wavelengths in the higher frequencies (about 8,000) mav 

 be employed to kill bacteria. The action of high frequency sound 

 waves appears to be similar to the action of sudden release of 

 pressure from bacterial cultures, namely a disruption of the cell 



