DAIRYING 145 



(3) Phenol phthalein, two or three drops. 



(4) A burette. This is a graduated glass 

 tube divided into twenty-five equal divisions, 

 or cubic centimetres. Each cubic centimetre 

 is subdivided into ten parts. Each large 

 division denotes .1 of i%. 



(5) A pipette capable of holding ten cubic 

 centimetres. 



(6) A porcelain dish. 



Method The burette is filled to the top with 

 soda solution. Ten cubic centimetres of milk, 

 accurately measured in the pipette, are run into 

 the porcelain dish, and two or three drops of 

 phenol are added, and the dish placed on the 

 stand under the burette. The soda is then 

 run in very carefully, and stirred gently until 

 a very faint crimson tint appears. The acid 

 originally present in the milk has now been 

 destroyed. The number of divisions of soda 

 used is then carefully read and noted. 



Thus, if two large divisions have been con- 

 sumed to neutralise the acid in the milk, the 

 percentage of acid denoted is .2. 



VI. 



