CH. VI.] LIPASE. 159 



washings to its appropriate beaker. Repeat this with another 10 cc. 

 of alcohol. To each beaker add 5 drops of i per cent, phenol 

 phthalein and titrate with o-i N. NaOH to a faint definite pink. 

 The results vary considerably with different preparations, but the 

 following may be taken as an example : 



A required 6-7 cc. of o-i N. NaOH 

 B 2-3 

 C 14-9 



6-7 2-3 = 4-4 is a measure of the amount of fatty acid produced 



in A. 



14-9 2 -3 = 12-6 is a measure of the amount of fatty acid produced 



in C. 



It will be found that the presence of the bile salts materially 

 aids the digestion of the fat. 



1 68. Detection of lipase. Boil about 5 cc. of milk to destroy 

 bacilli that may ferment the lactose. Cool and add 2 cc. of the 

 pancreatic extract. Add about i cc. of a o-oi per cent, solution of 

 phenol red (see p. 24), and then enough of a 2 per cent, solution of 

 sodium carbonate to give the solution a distinct reddish tinge. 

 Divide into two portions, A and B. Boil B, and then cool it under 

 the tap. Place the tubes in a warm bath at 40 C., and examine 

 at intervals. A will become yellow if lipase is present, owing to the 

 hydrolysis of the emulsified fat of the milk into fatty acids. 



NOTE. The hydrolysis of casein by trypsin leads to a slight increase in 

 the concentration of hydrogen ions. For that reason it is preferable to use a 

 mixture of cream and water instead of milk. 



Glycerol. 



169. Treat a drop or two of glycerol in a test-tube with a 

 solution of copper sulphate and then with sodium hydroxide. A 

 blue solution is obtained, glycerol preventing the precipitation of 

 cupric hydroxide. (See Ex. 96, note 3.) 



170. Boil the solution thus obtained. Reduction does not 

 occur. 



