Condensed Milk and Milk Powder 



205 



volume of water. One cubic centimeter of this reagent is sufficient 

 for the quantities of milk mentioned below. Larger quantities may 

 be used without affecting the results of polarization. 



(b) Mercuric iodid with acetic acid. — Mix 33.2 grams of po- 

 tassium iodid, 13.5 grams of mercuric chlond, 20 c.c. of glacial 

 acetic acid, and 640 c.c. of water." 



DETERMINATION 



The milk should be at a constant temperature, and its specific 

 gravity determined with' a delicate hydrometer. When greater ac- 

 curacy is required, a pycnometer is used. 



The quantities of the milk measured for polarization vary with 

 the specific gravity of the milk as well as with the polariscope used. 

 The quantity to be measured in any case will be found in the fol- 

 lowing table. 



'Determination of Volume of Milk Sample 



Place the quantity of milk indicated in the table, in a flask 

 graduated at 102.4 c.c. for a Laurent or 102.6 c.c. for a Ventzke 

 polariscope (Mohr c.c). Add 1 c.c. of mercuric nitrate solution 

 or 30 c.c. of mercuric iodid solution (an excess of these reagents 

 does no harm), fill to the mark, agitate, filter through a dry filter, 

 and polarize. It is not necessary to heat before polarizing. In case 

 a 200 mm. tube is used, divide the polariscope reading by 3 when 

 the sucrose normal weight for the instrument is 16.19 grams, or by 

 2 when the normal weight for the instrument is 26.048. When a 



