1S1 



The following table shows the percent protein in butter by the Formol 



titration and official method: 



Official M. 



?tkod. 



F. 



jrmaldehyde, 



.65 







.59 



.48 







.47 



.46 







.42 



.48 







.50 



.60 







.68 



.45 







.42 



.42 







.40 



.41 







.41 



.49 







.52 



Procedure to estimate the protein in milk. To estimate the proteids in 

 milk, weigh out 10 or 20 grams, preferably 20 grams, in a tared beaker, about 

 150 to 200 cc. capacity. Add 1 ce. of phenolpthalein solution, then run in 

 from a burette ~ XaOH until decided pink color is produced, a little practice 

 will enable one to carry the shade of color in mind. Then add 10 cc. of 

 neutralized formaldehyde, stir with a glass rod. when well mixed add 

 ^5 XaOH until the same shade of pink is produced as that before the form- 

 aldehyde was added (note this last addition of alkali). For example, if 7 ce. 

 of ;) t XaOH were required to neutralize the acidity produced on addition 

 of formaldehyde to 20 cc. of milk, then as in the case of butter: 



.0864X100X7 , . . o r>oi 



^- = percent protein = 3.024 



If we wish to estimate the casein alone and assuming the casein and 

 albumen are in proportion of 3 per cent, casein and .5 per cent, albumen, 

 then by using the equivalent of .075. we have as above: 



.075X100 X7 . • o ro 



20 = P erc ' en t casern =2.62 



The following table gives the results of the three volumetric methods 

 compared with the official methods on the same sample of milk: 



