METHODS OF EXAMINING MILK 289 
amber colored bottle, well stoppered and in a cool place. 
High temperatures break up the compound. The bottle 
should be closed immediately after being opened to draw 
off any of the solution. The solution must be tested by 
titration from time to time in order to insure accurate re- 
sults. 
To overcome the inconvenience of frequent tests of 
the hydrogen peroxide solution, the N. Gerber Co., of 
Leipsig, Germany, has prepared a tablet containing the 
hydrogen peroxide in more stable form. One of these 
tablets dissolved in 5 c.c. of water makes a 1 per cent. 
solution of hydrogen peroxide. (It has also been estab- 
lished by extensive experiments that one of these tablets 
added to 10 c.c. of milk will give the same result as 3 c.c. 
of a 1 per cent. hydrogen peroxide solution in 9 c.c. of 
milk). 
The test is made as follows: 1. The bottles must 
be well cleaned and sterilized by boiling for 15 minutes 
before using. The use of water containing calcium must 
be avoided. If not used at once the bottles are to be 
tightly corked with rubber stoppers, which are also to 
be sterilized by boiling. The bottles may be closed with 
cotton plugs and sterilized in a hot-air sterilizer. Pipettes 
should be sterilized before beginning a series of tests. 
The pipette used for measuring the milk should be 
washed out with cold water and then sterilized by filling 
it with boiling water after each sample of milk is meas- 
ured. 
2. Three c.c. of a 1 per cent. solution of hydrogen 
peroxide is placed in the bottle; then 9 c.c. of the milk to 
be tested is added. The bottle is numbered to correspond 
with the sample of milk. In testing individual milk, it 
is recommended that the sample be taken from the entire 
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