DAIRY LABORATORY GUIDE 



19 



FERRINGTON TEST 



Apparatus : Samples to be tested, 100 c. c. graduate, white 

 cup, Ferrington's alkaline tablets, and a 17.5 c. c. pipette. 



Preparation of Alkali Solution. Dissolve five of the pre- 

 pared tablets in 97 c. c. of warm, preferably distilled, water 

 or soft water. Keep in a tightly stoppered bottle when not 

 in use. It is necessary to prepare a fresh solution frequently, 

 as it will lose its strength within a few days. 



Steps: 1. With a pipette transfer to a white cup 17.5 

 c. c. of the sample to be tested; then add the alkali from a 

 graduate or from a burette until a permanent pink color 

 remains. 



2. In reading the results, the number of c. c. of the alka- 

 line solution required to bring the permanent pink color indi- 

 cates the number of hundredths of one per cent of acid present. 

 For instance, if 25 c. c. of alkali are required, it indicates that 

 .25% of acid is present. 



Data: 



