181 
The following table shows the percent protein in butter by the Formol 
titration and official method: 
Official Method. Formaldehyde. 
165 .59 
48 AT 
46 .42 
.48 31330) 
60 68 
45 42 
42 .40 
41 4] 
49 spe 
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 ce. capacity. Add 1 ec. of phenolpthalein solution, then run in 
from a burette Ey NaOH until decided pink color is produced, a little practice 
will enable one to carry the shade of color in mind. Then add 10 ce. of 
neutralized formaldehyde, stir with a glass rod, when well mixed add 
io NaOH 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 X NaOH were required to neutralize the acidity produced on addition 
of formaldehyde to 20 ec. of milk, then as in the case of butter: 
.0864 X 100 X7 
20 
If we wish to estimate the casein alone and assuming the casein and 
= percent protein = 3.024 
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: 
075 X 100 X7 
tae, Oa 
The following table gives the results of the three volumetric methods 
= percent casein = 2.62 
compared with the official methods on the same sample of milk: 
