172 GENERAL MICROBIOLOGY 



of liquid, measure the distillate and determine its specific 

 gravity*) and estimate percentage of yield. 



6. Weigh the potash bulb to find the amount of CO2 

 given off. Does it correspond to the yield of alcohol? 

 Explain. Are your results according to theory? 



6. Write the chemical equation for each change, giving 

 the specific enzymes concerned in each reaction. What 

 types of enzymes are concerned? 



7. Would alcohol be formed in bouillon containing no 

 sugar? In a 5% aqueous solution of sugar? Why? 



What fermentable substances are present in ordinary 

 meat bouillon? 



8. State your results in full and draw any conclusions 

 warranted. What practical applications may be made of 

 the above? 



REFERENCES 



MARSHALL: Microbiology, pp. 135, 140-141. 



LAFAR: Technical Mycology, Vol. II, Part II, pp. 473-481, 511-515. 



HAWK: Physiological Chemistry, 4th Ed., pp. 255, 357. 



EXERCISE 7. TO DEMONSTRATE THE NECESSITY 

 OF NITROGEN IN SOME FORM FOR MICROBIAL 

 GROWTH 



Apparatus. Four tubes each of: 



Ordinary broth (organic nitrogen, soluble albumins and 

 proteins) . 



Dunham's solution (organic nitrogen, soluble peptone, 

 no albumen). 



Uschinsky's asparagin medium (organic nitrogen, pro- 

 tein-free) . 



Cohn's solution (inorganic nitrogen combined with 

 organic acid). 



* Table for determining per cent of alcohol from specific gravity 

 in Sadtler's Industrial Organic Chemistry (1912), pp. 579-584. 



