If the volumetric method is used and the solution is of the N e^Tjct strength directed 

 above, milk sugar may be calculated as follows: 



100 X 0.067 

 X0.02 : 



wherein L is the per cent of lactose, and S the number of cubic centimeters of milk 

 solution prepared as above necessary to reduce 10 cc of Fehling's solution. 



Cane sugar. Determine by difference, deducting the milk solids (milk sugar -f- 

 proteids -f fat + ash ) from the total solids. 



[Note by Editor. No volumetric method having been adopted by 

 the association, it is suggested that the official method for the deter- 

 mination of lactose (Bui. 46, p. 41) be employed.] 



Twenty-second Convention, 1905, Bui. 99, Cir. 26. 



The following method for the determination of added water in milk 

 was adopted as provisional: 



DETECTION OF ADDED WATER. a 



To 100 cc of milk at a temperature of about 20 C. add 2 cc of 25 per cent acetic acid 

 (sp. gr. 1.0350) in a beaker, and heat the beaker, covered with a watch glass, in a 

 water bath for 20 minutes at a temperature of 70 C. Then place the beaker in ice 

 water for 10 minutes and separate the curd from the serum by filtration through a 

 12.5 cm plaited filter. 



Transfer about 35 cc of the serum to one of the beakers that accompany the 

 control-temperature bath used in connection with the Zeiss immersion refractometer, 

 the bath being of the type with openings in the top for 10 beakers. Place the 

 beaker in one of the openings, use the ground-glass strip at the bottom of the bath, 

 and by means of the regular refractometer heater or similar device maintain a con- 

 stant temperature of exactly 20 C. in the water surrounding the beaker, using a deli- 

 cate thermometer, reading to tenths of a degree. Immerse the end of the refractom- 

 eter in the serum in the beaker, and when the temperature is exactly 20 C. take the 

 reading on the scale. 



If the temperature varies from 20 C., the reading may be calculated on that basis by 

 means of a correction table. A reading below 39 indicates added water; between 

 39 and 40 the sample is suspicious. 



aVilliers and Bertault, Bui. soc. chim. Par., 1898, 19: 395; Matthes and Miiller, Zts. offentl. 

 Chem., 1903, 20: 173; Leach and Lythgoe, J. Am. Chem. Soc., 1904, 26: 1195. 



ERRATUM. 



On page 146, "Table X. Per cent of fat and solids not fat in milk," 

 make the following transposition: 



Columns 30, 31, 32, sections beginning 8.36, 8.61, 8.10, to the bot- 

 tom of the page, transfer column 32 to column 30, column 30 to 31, 

 and 31 to 32. 



IV. CEREAL PRODUCTS. 



In 1902 the associate referee, Mr. A. M. McGill. offered methods 

 for the examination of cereal products for study, which were printed 

 as an unnumbered circular of the Bureau of Chemistry and distributed 

 for criticism. No further action has been taken. 



28189 No. 2906 2 



