44 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



as small scales, which melt at 52 C. It is tolerably soluble in 

 hot and less soluble in cold water ; readily soluble in alcohol, 

 ether, chloroform,, benzol, and petroleum ether. It forms a 

 combination with picric acid, consisting of red needles, which 

 are decomposed on heating with caustic soda, but pass over 

 without decomposition when distilled with ammonia. Indol 

 has a peculiar excrementitious odor. 



Skatol crystallizes in small plates, which melt at 95 0. It 

 is less soluble in water than indol, but in the presence of. 

 steam it distils readily. It is readily soluble in alcohol, 

 ether, chloroform, and benzol. With picric acid it forms a 

 crystalline compound, which does not decompose on being 

 heated with caustic soda, but passes unchanged into the distil- 

 late. It has an intense fetid odor. 



Ordinary or Fermentation Lactic Acid, 



C 3 H e O s or OH 3 .OH.OH.COOH. 



Preparation. 330 grms. cane-sugar and 0.5 grm. tartaric 

 acid are dissolved in 1750 c.c. boiling water and allowed to 

 stand for two days. Then add 4 grms. putrefying cheese 

 (German Handkase), 440 grms. sour milk, and 135 grms. 

 zinc white, and allow this mixture to stand for eight to ten 

 days at 40 0. with constant shaking. After this time heat to 

 boiling, filter, and allow to cool, when zinc lactate will crystal- 

 lize out. This is purified by recrystallization and then de- 

 composed by H 3 S in hot aqueous solution, the solution fil- 

 tered, and the filtrate evaporated on the water-bath. The 

 syrupy residue is dissolved in ether (to separate any mannite), 

 and then the ether removed by distillation or by evaporation. 



Properties. Fermentation lactic acid has a similar appear- 

 ance to sarcolactic acid, namely, a colorless, faintly yellowish, 

 acid-reacting syrup, which mixes in all proportions with water, 

 alcohol, or ether. It is optically inactive. It forms salts 



