1917] AGRICULrUBAL CHEMISTEY — AGEOTECHNY. 507 



pp. 490-492). — From some preliminary experimental data the following pro- 

 cedure was devised : 



From 50 to 75 cc. of the sample used for direct polarization is placed in a 

 100-cc. flask and heated in the water bath to G5° C. In case a 50-cc. sample is 

 used 25 cc. of water should be added. After removal from tlie bath 10 cc. of a 

 mixture of equal volumes of hydi'ochloric acid (specific gravity I.ISS) and 

 water is added, the mixture allowed to cool spontaneously in the air for 15 

 minutes, and then in water to room temperature. It is made up to 100 cc. and 

 polai'ized as usual. 



A method for the estimation of levulose in presence of glucose, L. Loewe 

 (Proc. Soc. Expt. Biol, and Med., 13 {1916), No. 4, pp. 71-73).— The following 

 qualitative test is described : 



To 1 cc. of the sample, from 6 to 8 drops of orcein solution (0.2 per cent 

 aqueous solution) and 1 cc. of 85 per cent phosphoric acid are added. The 

 test tube is heated to boiling over a free flame and placed in a boiling water bath 

 for ten minutes. In the presence of levulose a yellow color appears, the depth 

 of which is proportionate to the concentration of the sugar. On cooling, a 

 yellow precipitate settles out. Upon the addition of sodium or potassium 

 hydroxid sufficient to neutralize the acid the yellow color changes to a distinct 

 orange. 



The development of this characteristic orange color was made the basis for 

 a quantitative determination of levulose, using suitable standards. In the 

 qualitative test levulose was detected in 1 cc. of a 0.005 per cent solution. 

 Maltose, lactose, galactose, and arabinose in solutions of various strengths did 

 not interfere with the tests. Cane sugar yielded a positive test, due to the 

 presence of levulose, from the cleavage of the sugar in the presence of the 

 phosphoric acid. 



The determination of fat in certain milk products, C. K. Francis and D. G. 

 Morgan {Oklahoma Sta. Bui. II4 {1917), pp. S, fig. ^).— The following modified 

 Babcock procedure for the determination of fat in ice cream and evaporated 

 milk is described : 



To 9 gm. of a uniform sample weighed in a 30 per cent cream test bottle 

 from 4 to 5 cc. of a mixture of equal parts of glacial acetic and sulphuric acids 

 is added with thorough mixing after each addition until a dark brown color 

 develops. Two or three additions of one or two drops of concentrated nitric 

 acid are now made and the mixture thoroughly agitated after each addition. 

 The amount of nitric acid added may be increased, but precautions should be 

 observed so that there is no loss through excessive foaming. When a light 

 yellow color results the bottle is immersed in boiling water for from 3 to 4 

 minutes until the dark brown color returns. The mixture is then centrifugal- 

 ized for 5 minutes, the bottle filled nearly to the neck with hot water, and 

 again centrifugalized for 10 minutes. The fat column is brought into the scale 

 of the neck with more hot water and again centrifugalized for another minute. 

 The meniscus is reduced with glymol and the reading multiplied by two for a 

 9-gm. sample. 



For malted milk, from 1 to 1.5 cc. at a time of a mixture of sulphuric and 

 nitric acids (20 cc. HsSO* to 1 cc. HNO3) is added to a 4.5-gm. sample in a 30 

 per cent cream test bottle until a light yellow color is obtained. About 15 or 

 20 cc. of the acid mixture is usually required. The bottle is then immersed 

 in boiling water until a dark brown color develops. A mixture of sulphuric 

 and nitric acids (10 cc. H2SO4 to 2.5 cc. HNO3) is added, 1 cc. at a time, with 

 thorough shaking after each addition, until a light red color is developed. It 

 is again immersed in boiling water until the dark brown color returns, cen- 

 trifugalized for 5 minutes, hot water added, arid again centrifugalized for 2 



