62 MILK 
water, the mixture is heated, precipitated with a 
small amount of alcohol and a convenient 
volume filtered. The filtrate is evaporated to 
half its bulk. The presence of an alkali-carbon- 
ate is easily ascertained by the usual tests. 
Borates.—Jenkins’ method is convenient and 
reasonably delicate. 10 c.c. of milk are mixed 
with 7 c.c. of hydrochloric acid, filtered, a.strip 
of turmeric paper dipped in the filtrate, and then 
dried on a watch-glass on the water-bath. The 
paper becomes red in the presence of borates. 
A simple test is to mix in a porcelain basin a 
drop or two of the milk, a drop of hydrochloric 
acid and a drop of alcoholic solution of turmeric 
and evaporate to dryness on the water-bath. 
The residue touched with ammonium hydroxid 
will show a distinct greenish stain in the presence 
of very small amounts of borates. 
It is obvious that the delicacy of both these 
tests may be materially increased by concen- 
trating the sample. As boric acid is volatile 
with steam it is best to render the sample slightly 
alkaline with sodium hydroxid befere evaporating. 
Abrastol (Asaprol).—This is a calcium beta- 
naphthol-sulphonate that has marked antiseptic 
powers and has been used as a food preservative. 
The following test suggested by Leffmann will 
detect very small amounts. 10 c.c. of the 
sample are mixed with 0.5 c.c. of the solution of 
