ACID PRODUCTION 28 1 



(5) Qualitative (of all the organic acids present). 

 Medium Required: 



Sugar (glucose or lactose) bouillon as in quantitative examina- 

 tion. 

 Reagents Required: 



Hydrochloric acid, concentrated. 



Hydrochloric acid, 25 per cent. 



Sulphuric acid, concentrated (pure). 



Phosphoric acid, concentrated solution. 



Ammonia. 



Ammonium sulphate. 



Baryta water. 



Sodium carbonate, saturated aqueous solution. 



Absolute alcohol. 



Ether. 



Calcium chloride. 



Calcium chloride solution. 



Zinc carbonate. 



Copper sulphate saturated aqueous solution. 



Alcoholic thiophene solution (0.15 c.c. in 100 c.c.). 



Animal charcoal. 



Five per cent, sodium nitroprusside solution. 



Potassium bichromate. 



Schiff's reagent. 



Arsenious oxide. 



Ferric chloride, 4 per cent, aqueous solution. 



Silver nitrate, i per cent, aqueous solution. 



Lugol's iodine. 



Ten per cent, caustic soda solution. 



Hard paraffin wax (melting-point about 52 C.). 



METHOD. 



1. Prepare cultivation in bulk (500 c.c.) in a litre 

 flask and add sterilised precipitated chalk, 10 grammes. 

 Incubate at the optimum temperature. 



2. After incubation throw a piece of paraffin wax 

 (about a centimetre cube) into the cultivation and 

 connect up the flask with a condenser. 



The paraffin, which liquefies and forms a thin layer 

 on the surface of the fluid, is necessary to prevent 

 the cultivation frothing up and running unaltered 

 through the condenser during the subsequent process 

 of distillation. 



3. Distill over 200 to 300 c.c. 



