Chemical Analysis of Milk and its Products. 229 



The ash is dissolved in water to which a little hydro- 

 chloric acid has been added, and the solution filtered. 

 A strip of tumeric paper moistened with the filtrate will 

 be colored reddish brown when dried at 100 C. on a 

 watch glass, if boracic acid is present. 



If a little alcohol is poured over the ash to which con- 

 centrated sulfuric acid has been added, and fire is set to 

 the alcohol after a little while, it will burn with a yel- 

 lowish green tint, especially noticeable if the ash is 

 stirred with a glass rod and when the flame is about to 

 go out. 



291. The following modification of the first test given is said 

 to show the presence of only a thousandth of a gram of borax 

 in a drop of milk (about .15 per cent.): 1 



Place in a porcelain dish one drop of milk with two drops of 

 strong hydrochloric acid and two drops of saturated tumeric 

 tincture; dry this on the water bath, cool and add a drop of 

 ammonia by means of a glass rod. A slaty blue color changing 

 to green is produced if borax is present. 2 



292. b. Bi-Carbonate of soda. 100 cc. of milk to which 

 a few drops of alcohol are added, are evaporated and 

 carefully incinerated; the proportion of carbonic acid in 

 the ash as compared with that of milk of known purity 

 is determined. If an apparatus for the determination of 

 carbonic acid is available, like the Scheibler apparatus, 

 etc., the per cent, of carbonic acid per gram of ash (and 

 quart of milk) can be easily ascertained. Normal milk 

 ash contains only a small amount of carbonic acid (less 

 than 2 percent.), presumably formed from the citric acid 

 of the milk in the process of incineration. 



1 N. J. Dairy Commissioner, report 1896, p. 37. 



2 See also 139, 144. 



