DETERMINATION OF SPECIFIC GRAVITY 601 



Apparatus Needed. One Soxhlet-Henkel titration apparatus 

 consisting of one 50 c.c. graduated burette with pinch cock ; one solu- 

 tion bottle with double perforated stopper and equipped with rubber 

 bulb and connection with burette ; one 50 c.c. pipette for measuring 

 cream ; one white cup or porcelain dish ; one 2 c.c. pipette for meas- 

 uring the indicator. 



Reagents Needed. One-fourth normal solution of sodium 

 hydrate and an alcoholic solution of phenolphthalein. 



Making the Test. With 50 c.c. pipette pour 50 c.c. of the 

 cream to be tested into the white cup. Add 2 c.c. of the phenolphtha- 

 lein indicator. Fill the burette to the top graduation with the alkaline 

 solution from the bottle by pressing the rubber bulb. Then draw 

 from the burette enough of the alkaline solution into the cup until 

 after rotating the cup, or stirring the contents, a faint pink color 

 remains. The number of cubic centimeters of the alkaline solution 

 required, as shown on the graduation of the burette, are termed 

 degrees of acid. Each cubic centimeter of the one-fourth normal 

 alkaline solution represents one degree of acid. 



This method was later modified by Soxhlet-Henkel to the extent 

 of using 100 c.c. of cream instead of 50 c.c. and increasing the phe- 

 nolphthalein from 2 c.c. to 4 c.c. Here again each cubic centimeter 

 of one-fourth normal alkaline solution required to neutralize the acid 

 in the cream represents one degree of acid. In this case one degree 

 of acid is equivalent to .0225 per cent acid, or 1.25 c.c. of decinormal 

 alkaline solution of Mann's test. In stating the degree of acid 

 by the Soxhlet-Henkel method it is necessary therefore to know 

 whether they refer to the use of 50 c.c. or of 100 c.c. of cream. 



DETERMINATION OF SPECIFIC GRAVITY OF MILK 

 SKIM MILK, CREAM AND BUTTERMILK 



Definition. By the specific gravity of a liquid is meant the 

 weight of a given volume of the liquid, such as milk, skim milk, 

 cream, etc., as compared with the weight of the same volume of 

 water at the same temperature. The specific gravity of water is 1. 

 That is, one cubic centimeter of water weighs one gram. Milk is 

 heavier than water, therefore its specific gravity is greater than that 

 of water. Average milk has a specific gravity of 1.032. The specific 

 gravity is usually determined or calculated at a temperature of 60 F. 



The specific gravity of liquids is readily determined by means 



