HYPOCHLORITES AND CHLORAMINS IX MILK AND (REAM. 3 
discolored when compared with the control. This holds good for 
both hypochlorites and chloramins. 
In case the milk contains an amount of hypochlorite corresponding 
approximately to 1 part of chlorin in 5,000 parts of milk, then the 
milk acquires a pale-yellow color on the addition of the iodid solu- 
tion, and the color deepens as the amount of chlorin increases, so that 
at 1 : 1.000 dilution the milk has a yellowish-brown color. At 1 : 5,000 
dilution the yellow color is not permanent and fades gradually. If 
kept at room temperature it is necessary to add hydrochloric acid 
at 1 : 5.000 dilution in order to bring out the yellow color. With 
chloramins a yellow color is produced at 1: '2.500 dilution. If less 
chlorin is present than mentioned above, the milk retains its natural 
color. 
In more dilute solutions of hypochlorites and chloramins it i- 
necessary to heat the milk-iodin-hydrochloric-acid mixture in order 
to bring about the reaction. The cooling is necessary to prevent a too 
rapid decomposition of the iodid by the excess of hydrochloric acid. 
With hypochlorites and chloramins the curd and the solution 
below acquire a distinct pale-yellow color with 1 part of chlorin in 
50.000 parts of milk. The shade of the color varies somewhat and is 
a little paler with chloramins than with hypochlorites. The liquid 
below the curd is also colored yellow, the shade corresponding to the 
depth of color of the curd. 
When milk which has stood at room temperature for 24 hour- is 
treated as above, the coloration produced is a little paler than when 
kept at ice-box temperature. 
The curd of the control which has been kept at ice-box temperature 
shows only a slight yellowish tinge when compared Avith the curd 
of a blank which contains no iodid. The liquid below the curd in the 
control, however, is most distinctive, since it shows no trace of yel- 
low when compared with the blank containing no iodid. 
The addition of starch to the liquid below the curd brings out the 
reaction somewhat more prominently by changing the pale-yellow 
color to a light-reddish purple, the coloration passing through red 
purple into a deep-blue purple as the amount of the chlorin present 
increases. The control is also slightly discolored by the addition of 
starch and may acquire a light-straw color, but without any trace of 
a red-purple tint. 
In milk which has been kept at room temperature for a long time, 
the control may have a stronger straw color, but without any trace of 
purple. On this account it is best to judge the presence of small 
amounts of hypochlorites and chloramins by the color of both the 
curd and the liquid below. 
