82 



MILK AND DAIRY PRODUCTS PART 



quantity (40-50 c.c.) ^/10H 2 SO 4 along with a few drops of 

 cochineal or lacmoid solution. The point of the distillation tube 

 must always be well below the surface of the sulphuric acid. 

 After three-quarters of an hour all the ammonia has usually 

 distilled over, and the sulphuric acid can be titrated with 



FIG. 46. Apparatus for Kjeldahl's Method. 



N/1Q caustic soda or JV/10 baryta water, and in this way the 

 nitrogen which has been absorbed as ammonia by the sulphuric 

 acid is estimated. As casein, according to Hammarsten, 

 contains 15*65 per cent, nitrogen, and lacto-albumin 15'77 per 

 cent, according to Sebelien, the amount of protein in milk is 

 obtained by multiplying the nitrogen found by 6*37. 



