Condensed Milk and Milk Powder 229 



detection of lime in milk 1 



Shake 250 c.c. of milk at 15 degrees C. with 10 c.c. of a 10 per 

 cent, solution of hydrochloric acid. Let stand at room temperature 

 for half an hour. Filter, returning the first portion of filtrate to the 

 filter." Cover filter to prevent evaporation. 



Pour 104 c.c. of the filtrate (equal to 100 c.c. of milk) into a 

 200 c.c. flask, add 10 c.c. of a 10 per cent, solution of ammonia and 

 fill the flask to the mark with water at 15 degrees C. Let stand for 

 thirty minutes. Filter through folded filter, pouring back on the 

 filter the first portion of the filtrate. Test 100 c.c. of filtrate (equiv- 

 alent to 50 c.c. of rnilk) with 10 c.c. of 5 per cent, ammonium 

 oxalate solution and proceed with the determination of the lime in 

 the usual way, but without warming the liquid. 



According to Baier and Neumann and corroborated by Luhrig, 

 in normal milk the lime in the serum is present to the extent of 

 thirteen to eighteen milligrams per 100 c.c. In milk to which 

 sucrate of lime has been added the results are correspondingly 

 higher. 



DETECTION OF GELATIN 2 



"Prepare an add solution of mercuric nitrate by dissolving mer- 

 cury in twice its weight of nitric acid of 1.42 specific gravity, and 

 diluting this solution to twenty-five times its bulk with water. To 

 io c.c. of the milk or cream to be examined, add an equal volume of 

 the acid mercuric nitrate solution, shake the mixture, add 20 c.c. of 

 water, shake again, allow to stand five minutes, and filter. If much 

 gelatin is present the filtrate will be opalescent and cannot be ob- 

 tained quite clear. To a portion of the filtrate contained in a test 

 tube, add an equal volume of a saturated aqueous solution of picric 

 acid. A yellow precipitate will be produced in presence of any con- 

 siderable amount of gelatin, while smaller amounts will be indicated 

 by a cloudiness. In the absence of gelatin the filtrate obtained will 

 remain perfectly clear." 



DETECTION OF PRESERVATIVES 



CARBONATE OR BICARBONATE OF SODA 1 (BULGER'S METHOD) 



Dilute 50 c.c. of milk with 250 c.c. of water. Heat and precipi- 

 tate with a small quantity of alcohol. Filter, evaporate the filtrate 



1 Barthel, Milk and Dairy Products 



2 United States Department of Agriculture, Bureau of Chemistry, Bulletin 107, 1912 



