1010] AGRICULTURAL CHEMISTRY — AGROTECHNY. 613 



Simplified preparation of the alkaline copper solution for the detection 

 and determination of sugars, B. .Jistin-Mikiikk (Jour. I'linrm. rt Cliim., 7. 

 scr., in \I919), No. l, pp. 18-20).— The author states thai by adding 20 cc. of 

 a 10 per cent copper sulphate solution slowly to 100 ce. of a 33.G0 per cent 

 solution of sodium hydroxid (density 1.37) a stable solution can be made with- 

 oiit tbe use of organic salts, such as tartrates, and that 1 1 1« - solution can be used 

 successfully In place of the more complicated Fehltng's solution. 



The determination of fructose in the presence of aldoses, O. Lknart 

 (/.ts.hr. Per. Devt. ZuckerinduM., 1918, No. 752, II, pp. S.-i'>-.i.' f (>).— In connec- 

 tion with the investigation previously noted (E. S. R., 40, p. r>07), a study Is 

 reported of the influence of various catalyzers, such as metallic salts, todin, 

 and sulphur, on the oxidation of glucose, fructose, sucrose, and raffinose by 

 broniin. Precipitated sulphur was found to be the most active catalyzer. For 

 samples of fructose containing polyoses, hydrolysis before bromination is 

 recommended. The oxidation of dextriu with bromin was found to be incom- 

 plete even after seven days. 



The determination of lactose in milk heated after addition of sodium bi- 

 carbonate, C. PoBCHEB and A. Bonis (Ann. Falsi/., 11 (1918), No. 119-120. \>\t. 

 295-899, //'.'/. /). — The authors recall the results obtained by Jensen and Plan- 

 ner i E. S. U., 17, p. 2S9) on the action of heat upon cow's milk, and report 

 similar experiments, including the effect of heat upon milk to which various 

 amounts of sodium bicarbonate had been added. 



Determinations of lactose were made by the polarlmetric and reduction 

 methods. Pasteurised milk underwent no change in color. Heated in the 

 autoclave at 120° C, milk without bicarbonate turned brown In from 40 to 60 

 minutes. Milk with bicarbonate turned brown in proportion to tbe amount of 

 bicarbonate and the time of heating. Samples containing 2 gm. of bicarbonate 

 per liter became a rich coffee color in one hour. 



The reducing power of lactose is less affected than the rotatory power. The 

 authors are of the opinion that the diminution of rotatory power is due not 

 so much to changes taking place in the casein as suggested by Jensen as to an 

 alteration in the lactose, and advise caution in the use of the polariineter for 

 the determination of lactose in sterilized milk. 



The relation between the oxygen concentration and rate of reduction of 

 methylene blue by milk, E. N. Harvey (Jour. Gen. Physiol. , 1 (1919), No. 4. 

 pp. 415-419, fg. 1). — The rate of reduction of methylene blue by milk and 

 acetaldehyde is shown to be proportional to the concentration of oxygen in 

 the milk, and it Is suggested that this fact may be made the basis of a method for 

 determining oxygen in gaseous mixtures. The gas to be tested may be shaken 

 with a mllk-acetaldehyde-methylene blue mixture and the end-point determined 

 by comparison with a similar tube of milk containing no methylene blue. A 

 control determination of the time necessary for decolorizatlon of mllk-acetal- 

 dehyde-methylene blue mixture shaken with air must be made under the same 

 conditions. 



It is stated that the rate of decolorization of methylene blue by milk can 

 be increased by raising the temperature or Increasing the concentration of the 

 reducing enzym by evaporating the milk in vacuo to from one-third to one- 

 fourth its volume. The addition of 2 per cent of sodium fiuorid to milk will 

 prevent the growth of bacteria without affecting its reducing powers during 

 a period of two months. 



Determination of saccharin in compressed tablets, A. Bonis (Ann. Falxif., 

 11 (IMS). X,,. 121-122. pp. 369S72).— As a supplement to the methods of de- 

 termining saccharin, previously noted (E. S. EL, 37, p. S04), tbe author outlines 



