New York Agricultural Experiment Station. 299 



c.c. of distilled water and 2 c.c. of a saturated solution of neutral 

 potassium oxalate, allow the mixture to stand not less than two 

 minutes and then titrate with T % NaOH. Since most solid potas- 

 sium oxalate is acid, care must be taken to prepare a solution that 

 is really neutral, which may be done in the following way: A 

 saturated solution of ordinary potassium oxalate is prepared and 

 decanted from the solid residue. To this solution is added 1 c.c. 

 of phenolphthalein solution and then, drop by drop, enough normal 

 NaOH solution to produce a permanent faintly pink coloration. 



In the following table is given the acidity of 21 samples of milk 

 from individual cows, as determined by the two methods, with 

 and without addition of neutral potassium oxalate. 



Potassium oxalate is a poisonous substance. If the method as 

 outlined above is used for the determination of the acidity of milk, 

 extreme care should be taken to see that the potassium oxalate 

 solution is kept in a bottle properly labeled and marked with the 

 word POISON. 



