86 LABOEATOKT BACTERIOLOGY. 



3. Butyric acid. 



A small portion of the solution to be tested is treated as in 

 the test for acetic acid and the presence of butyric acid is 

 shown by the peculiar odor of the ethyl butyrate produced. 



4. Lactic acid. 



Add 10 cc. of Uffelmann's solution to a little of the culture 

 in a test-tube. The formation of a canary yelloW color indi- 

 cates the presence of lactic acid. 



(Uffelmann's solution: 100 cc. of a 1% solution of car- 

 bolic acid to which 10-15 drops of a solution of Fefilg have 

 been added.) 



