ADDENDA. 



ESTIMATION OF FAT IN MILK. 



Morse and Piggot 1 describe a method of estimating fat in milk by pre- 

 vious desiccation with dehydrated sulphate of copper. About 20 grams 

 of the dried copper sulphate are placed in a porcelain mortar and 10 cc of 

 milk added to it, being careful that none of the milk comes in contact 

 with the mortar. The milk is dried in a very few moments, and the 

 mass is then rubbed up with & little clean sand and transferred to an 

 extraction tube. The mortar is then washed two or three times with 

 from 10 to 15 CC of benzine, and the fat is extracted by treating in the 

 extraction tube twelve times with the same quantity of benzine. The 

 flask which has received the solution of butter is now placed on a water- 

 bath and the volume of the solution reduced to 10 CC or less. The butter 

 fat is now saponified with 20 W of half normal solution of caustic potash. 

 The excess of alkali is determined by a standard solution of hydro- 

 chloric acid. The results obtained by this method agree closely with 

 the gravimetric determinations. 



ESTIMATION OF WATER IN MILK. 



The determination of water in milk is made in the following manner, 

 described by P. G. Short 2 : About 2 grams of milk are placed in a Hof- 

 meister capsule (schtilcheu) and dried at 110 C. in an oven containing 

 a solution of chloride of calcium, boiling at 110 C. 



When the fat is to be subsequently estimated the capsule is wrapped 

 in a piece of prepared cheese-cloth, crushed between the fingers, and 

 placed in an extraction tube. 



SUBSTANCES SOMETIMES ADDED TO MILK TO MASK THE REMOVAL OF 

 THE CREAM AND ADDITION OF WATER. 



Where much water is added sugar is most frequently used to increase 

 the specific gravity to the normal number. 



Chalk, salt, annotto, turmeric, gum, dextrine, and cerebral matter 

 have also been found in milk by Professor Weber. 



x Amer. Chem. Journ., vol. 9, p. 108. 3 Ainer, Cheiii. Jouru., vol. 9, p. 100. 



127 



