48 METHODS OF STUDYING MICROORGANISMS 



easily than hot moisture. Burning is the best of all methods, 

 and should be used for everything which can be spared, 

 handkerchiefs, dressings, and objects like magazines from the 

 sick room. 



The two thermometric scales are explained as follows: 



F. = Fahrenheit, the ordinary scale used in this country. Water just at 

 the freezing-point registers 32 F., while just at the boiling-point registers 

 212 F. The zero has no relation to physical changes. 



C. = Centigrade, the French system. Water just at the freezing-point 

 is C., and just at boiling-point is 100 C. 



The 100 in the Centigrade scale is equal to the 180 between 32 and 

 212 in the Fahrenheit scale. 



To change one system to the other proceed as follows: 



From Fahrenheit to Centigrade: Given degree F. 32-i-9X5 = same 

 degree in Centigrade scale. Example: 50 F. -32 =18 -=-9 =2X5 =10. 

 Therefore50F.=10C. 



From Centigrade to Fahrenheit: Given degree C. -i-5 X9+32 = same 

 degree in Fahrenheit scale. Example: 10 C. ^5=2X9=18+32=50 F. 



