46 MILK 
Gelatin produces a yellow precipitate. Picricacid 
will detect the presence of 1 part of gelatin in 
10,000 parts of water. The picric acid solution 
should not give a precipitate with the nitrate 
solution. 
For sucrose Cotton devised the following tests: 
ro c.c. of the sample are mixed with 0.5 gram 
of powdered ammonium molybdate, and 10 c.c. 
of dilute hydrochloric acid (1 to 10) are added. 
In a second tube, 10 c.c. of pure milk or 10 c.c. 
of a 6% solution of lactose are similarly treated. 
The tubes are then placed in the water-bath and 
the temperature gradually raised to about 80°. 
If sucrose is present, the milk will become blue, 
while genuine milk or milk-sugar remains un- 
altered unless the temperature is raised to the 
boiling-point. According to Cotton, the reaction 
is well marked in the presence of as little as 1 
gram of sucrose to 1000 c.c. of the milk. For 
the detection of other organic thickening agents, 
such as pectoses, agar and mixtures of agar and 
gelatin, see under ‘‘Cream,”’ page 67. 
Calcium Saccharate (Saccharate of Lime).—A 
compound produced by the action of lime on 
sucrose has been used as a thickening agent. A 
test due to Bauer and Neumann is recommended 
by Lythgoe, from whose description the following 
is taken: 
To 25 cc. of milk (or cream) add ro c.c. of 
