166 BACTERIOLOGICAL CHEMISTRY LESSON vm 



Test them as before with Fehling's solution, after 

 four to six hours, and again after twenty-four 

 hours : reduction of copper, no alcohol. 



(3) Heat some of the dry powder at 130 or 135 C. for 

 fifteen minutes, and repeat the previous experiment. 



On testing with Fehling's solution, no reduction of 

 copper or alcohol. 



Conclusions : 



Enzymes in solution are readily rendered inert by 

 heat. 



Enzymes in a solid and dry condition are destroyed 

 with difficulty by heat. 



