338 ReEPporRT OF THE CHEMIST OF THE 
(5) One small pipette with rubber bulb (so-called dropper), 
provided with a mark at the 1 cc. point. 
(6) Breakers or cups holding 200 cc. or more. Ordinary 
white porcelain tea-cups, or white granite-ironware cups an- 
swer the purpose. 
(7) Funnels, glass or granite-ironware, 3 to 4 inches in 
diameter. 
(8) Filter-paper cut round, 6 to 7 inches in diameter. In 
their place one can use fine linen cloth cut in proper size and 
Shape. These have the advantage of permitting repeated use, 
being washed always after use. 
(9) Measuring-cylinders, accurately graduated and holding 
000 SCG: 
SOLUTIONS. 
(1) Sodium hydroxid. This solution may be made most con- 
veniently by preparing a regular tenth-normal solution and 
then diluting 795 cc. of this to one liter. In such a solution, 
1 cc. corresponds to 0.09 gram of casein or 1 per ct. when 
one takes 9 grams of milk for testing. In actual practice, 
we take a 17.5 cc. (18 grm.) samplé of milk, but in the final 
part of the test use only one-half of the solution obtained. 
Alkali solutions made from alkaline tablets, such as are 
often used in dairy work for determining acidity of cream, 
milk, whey, etc., do not give satisfactory results in this test 
for casein. 
The simplest method of preparing the alkali solution is to 
purchase from a reliable chemical supply-house sodium hy- 
droxid, of the quality known as “strictly chemically pure,” 
put up in sealed, glass-stoppered bottles, each bottle contain- 
ing exactly 40 grams. The entire contents of the bottle, dis- 
solved in one liter of water, make a normal solution; and 
100 cc. of this normal solution, diluted with water to one 
liter, gives the tenth-normal solution, 795 ec. of which diluted 
to one liter makes the strength of solution desired when using 
17.5 cc. of milk for the test under the conditions stated above. 
