134 Testing Milk and Its Products. 



of boracic acid which will keep it sweet 36 hours, its acidity may 

 be increased to .35 per cent., in a sample of milk which pre- 

 viously tested perhaps only .15 per cent. acid. 



As before stated, unadulterated milk will usually smell or 

 taste sour or " turned, " when it contains .30-. 35 per cent, acid 

 (121) milk testing as high as this limit, which neither smells 

 nor tastes sour in any way, is therefore in all probability adul- 

 terated with some preparation containing boracic acid or a simi- 

 lar compound. 



152. "Alkaline tabs." These are not the alkaline tablets, 

 but a substitute which was put on the market by a New York 

 firm. The outfit furnished consisted of four packages of paper 

 discs made of filter paper, each of about the size of an old-style 

 copper cent; two packages of square paper; one glass of about 

 10 cc. capacity, and one small glass bottle. An investigation of 

 these "Tabs" soon disclosed the fact that they were entirely 

 inaccurate, and that no dependence could therefore be placed on 

 the results obtained by their use. 



Questions. 



1. What is the meaning of a one-tenth normal alkali solu- 

 tion? 



2. How are the results expressed in testing cream by the 

 Manns 7 test? 



3. What per cent, acidity is indicated by 35 cc. & alkali? 



4. If 20 cc. cream require 12 cc. * T *J alkali for neutralization, 

 what per cent, acid in the sample? 



5. If 1 cc. NJ alkali neutralize .009 gram lactic acid, what is 

 the per cent, of acid in a sample of cream, which required 12 cc. 

 alkali for 25 cc. of cream? 



6. What apparatus and strength of solution must be taken 

 to show per cent, acidity directly from cc. alkali used with Far- 

 rington's alkaline tablets? 



7. If cream testing 20% fat has an acidity of .6%, what will 

 be the corresponding acidity of cream testing 40% fat? 



8. Describe the rapid method of testing acidity of samples of 

 milk or cream by the alkaline tablet solution. 



9. What is the per cent, acidity in a sample that requires 

 2 oz. of standard tablet solution to give a pink color in 1 oz. of 

 milk? 



