124 Milk and Its Products 



Farrington's alkaline tablets offer a very convenient 

 means of selecting milks that are suitable or un- 

 suitable for pastuerizing purposes. For this purpose 

 it is convenient to make the tablet solution (see 

 Chap. X.) by dissolving one tablet in each ounce 

 of water, or one tablet in 30 c. c. of water. Then 

 with a cup or other convenient vessel and a small 

 measure of any suitable size, the comparative acid- 

 ity of different milks can be readily and quickly de- 

 termined as follows : Put a measure full of milk 

 into the cup and add two measures of the tablet 

 solution. If the color disappears, more than .2 of 1 

 per cent of lactic acid is present, and the milk is too 

 sour for pasteurizing purposes. If the milk remains 

 pink, less than .2 of 1 per cent of lactic acid is pres- 

 ent, and the milk may be safely used. If it is 

 desirable to measure the amount of acid, each meas- 

 ure of solution may be roughly taken to represent 

 .1 of 1 per cent of acid. Thus, if the pink color 

 remains when one measure of the solution has been 

 added, the milk contains .1 per cent of acid. If it 

 require four measures of the solution before the pink 

 color is permanent, the milk contains .4 per cent of 

 acid. A convenient measure for this purpose is made 

 by soldering a piece of stiff wire to the side of a 

 No. 10 cartridge shell, after the manner of a milk- 

 measuring dipper. 



