ANALYSIS OF MILK-PRODUCTS 45 



The milk sugar is found by the formula 



,,. i ioo 1.076 F X W 

 Milk sugar = R x X 0.95 X ^ 



Where R = Reading in angular degrees with a 



200 mm. tube. 



F = percentage of fat by weight. 

 W = weight of cream taken. 



The gravimetric estimation will require slight correc- 

 tion for the volume of the fat, and the formula 



ioo 1.076 F x W 

 Milk sugar = 2M X ^ may be used. 



M = weight of milk sugar obtained from the Table on 



1>- 34- 



The protein estimation is carried out as for milk ; 

 it saves time, however, to dry the cream and to extract 

 the bulk of the fat before submitting the sample to 

 Kjeldahl's method, as fat is attacked but slowly by sul- 

 phuric acid and mercury. 



Butter-milk is analysed in exactly the same way as 

 milk. 



It sometimes happens that when churning, both salt 

 and water find their way into the butter-milk ; when 

 the butter-milk is to be sold, it is important to be able 

 to rapidly estimate both the proportion of water and of 

 salt. 



Chlorides can be titrated in milk with silver 



nitrate solution, using potassium chromate as indicator, 

 but as milk itself contains chlorides a correction is 

 necessary for this. To 10 c.c. add a few drops of 



potassium chromate solution and run in silver 



10 



nitrate (see Appendix) till a faint red tinge is seen ; 

 from the quantity used subtract the aldehyde figure 

 (obtained with strontia) multiplied by 0.171; the 

 remainder multiplied by 0.0585 gives the sodium 

 chloride. 



By multiplying the amount of salt fcund by 0.00735 



