288 SALTING AND WORKING OF BUTTER 



cially if butter is medium soft, will cause too much water to be 

 incorporated in the butter. After the butter has been exposed 

 to the second brine the proper length of time, it should be drawn 

 off and the butter worked in the usual manner. Less working 

 is usually given to butter which has been salted by the brine 

 method. It should be worked enough to distribute the brine 

 evenly in the butter, and to bring the butter into a compact form. 

 If the butter salted by the brine method is not worked sufficiently, 

 it will become streaky in color after standing. 



SALT TEST 



Principle of the Test. -The reagent used is a solution of silver 

 nitrate (AgNOs), and the indicator is a solution of potassium 

 chromate (K^CrC^). The silver nitrate will combine with 

 either common salt (NaCl) or potassium chromate, but it has the 

 stronger affinity for salt. Hence, if we add a few drops of the 

 potassium chromate to a solution of common salt, and then 

 gradually add silver nitrate solution, the silver nitrate will com- 

 bine with the salt, forming white or colorless compounds. But 

 as soon as the salt is all used or taken up the silver nitrate com- 

 bines with the indicator, potassium chromate, producing a 

 brick-red compound. 



Chemical Changes that Take Place. First, as long as there is 

 free salt: AgNOs (silver nitrate) +NaCl (common salt)=AgCl 

 (silver chloride) +NaNOs (sodium nitrate). No colored sub- 

 stances formed. Second, after all the salt has been acted upon 

 2AgNOs+K2CrO4 (potassium chromate) = AgoCrCU (silver chro- 

 mate, brick-red) + 2KNO 3 . Brick-red color produced. 



Proportions in which Silver Nitrate and Salt Combine with 

 Each Other. 



Molecular weight of silver nitrate, 



AgNO 3 = 108 + 14+3 X 16 = 170 



Molecular weight of common salt, 



NaCl = 23 +35.5 = 58.5 

 Both are univalent. 



