360 BUTTEE. 



An approximation to the amount of butter in pounds that 

 may be obtained from milk by churning the separated cream 

 can be obtained by subtracting 0"1 from the percentage of fat, 

 multiplying the difference by /„, and by the number of gallons 

 of milk. 



Estimation of Water and Salt in Buttermilk. — It 

 sometimes happens that when churning both salt and water 

 find their way in the buttermilk ; when the buttermilk is to be 

 sold, it is important to be able to estimate rapidly both the 

 proportion of water and of salt. 



It was found that chlorides could be titrated in mOk with 



N . . . . . . . 



r— silver nitrate solution, using potassium chromate as mdicator, 



and that 10 c.c. of milk took on an average 3 '45 c.c. :r-r silver 



solution, with extremes of 3'35 c.c. and 3'6 c.c. in nine samples. 



N 

 It was further found that the number of c.c. of — silver solution 



for 10 c.c. of milk could be deduced with considerable accuracy 



N 

 by multiplying the aldehyde figure (obtained with y-r- strontia) 



by 0171, and subtracting this quantity from the quantity actually 

 used ; the remainder was a measure of the sodium chloride. 



A series of determinations showed that 1 gramme of sodium 

 chloride added to 100 c.c. of milk raised the density by 0'00735, 

 and by multiplying the amount of salt found' by this figure the 

 increment of density due to the addition is deduced, and sub- 

 tracting this from the density found, the density of the milk is 

 obtained. From this last figure and the fat the solids not fat 

 can be calculated, and from this the amount of added water 

 roughly deduced. 



The method is : — Estimate the specific gravitv, fat, and alde- 



N 

 hyde figure as usual ; titrate 10 c.c. of buttermilk with rr-r silver 



nitrate, using potassium chromate as indicator, till a reddish 

 colour is produced. From the volume of silver nitrate used 

 subtract the aldehyde figure x 0"171, and multiply the residue 

 by 0"0585, the product is the percentage of salt ; multiply this 

 by '00735, and subtract the resulting figure from the specific 

 gravity ; the percentage of added water, if present, is calculated 

 from the fat, and the corrected specific gravity in the same way 

 as the extent of watering of milk is deduced (p. 173). 



It is sometimes asserted that a certain amount of water (20 or 

 25 per cent.) is allowed to be added to milk or cream for churning 

 purposes. This view, however, appears to be quite incorrect ; 

 the addition of " breaking " water does not appear to be recognised 



