AGRICULTURAL CHEMISTRY AGROTECHNY. 809 



The reductase (fermentation reductase) test, R. Dons (Centhl. Bakt. [etc.], 

 2. Abt.. JfO (IHIJ,), A'o. IS, pp. i:i2-lM; nU. in licrUn. Tirrdrztl. Wrhnschr., 

 30 (J9J.'/), No. 22, p. 3S8). — The author eoncludos that the reductase test can not 

 serve as a substitute for the counting (plat in?;) of micro-organisms. In the 

 decolorization of the dye the organisms grown at 38° C. were very active, and 

 the results varied with pure cultures according to whether raw, pasteurized, or 

 sterilized milks were tested. He believes that the micrococci and streptococci 

 which form lactic acid probably decide the outcome of the reductase test. 

 Bacteria of the coli aerogenes group reduced methylene blue as i-apidly as true 

 lactic acid bacteria, but more slowly in milk which had been pasteurized and 

 sterilized. The test, however, will not decide how many bacteria are present. 

 Bacteria which do not grow at 3S°, or do so only sparingly, reduce methylene 

 blue only when they are present in large numbers. An addition of human or 

 horse feces to ordinary milk did not (even in large amounts) influence the 

 reductase test when the milk had stood for two hours after adding the excre- 

 ment. 



Milk which had been heated for a long time at 100° or for a short time at 

 135° was capable of reducing methylene blue. JMilk heated 10 minutes at 08 to 

 70° still produced the reductase test as in raw milk. The presence of a small 

 amount of methylene blue in milk will check the development of bacteria, and 

 the use of the reductase test in conjunction with the fermentation test was not 

 tested by the author because it seemed to be of no value from a hygienic stand- 

 point. 



Manufacture and use of unfermented grape juice, G. C. Husmann ( U. 8. 

 Dept. Agr., Farmers' Bui. 6U (1915), pp. 16, figs. /.'/). — "It is the purpose of 

 this publication to state briefly the way in which unfermented grape juice is 

 made and px'eserved, both for commei'cial and .domestic use, as well as the funda- 

 mental i)rocesses and principles involved, and to offer practical suggestions." 

 The subject is dealt with under the following headings : Composition of the 

 grape; analyses of grape must; causes of fermentation; methods of preventing 

 fermentation; flavor and quality of grape juice; home manufacture of grape 

 juice ; valuable appliances for home use ; commercial methods of making must ; 

 and the use and food value of unfermented grape juice. A few thoroughly 

 tested recipes prepared with unfennented grape juice are included. 



Some abnormal factors of so-called farmers' cider vinegars, J. C. Diggs 

 (Jour. Indus, and Engin. Clicm.. 6 (lOlJf), ^'o. 3, pp. 215, 216). — This gives the 

 results of examining 18 samples of cider vinegar which were entered in an 

 apple product exhibit of an apple show held in Indiana. 



" The results of these analyses show the uncertainty of unscientific methods 

 In the manufacture of vinegar. Pernicious practices exist among farmers who 

 put vinegar on the market. Fraudulent vinegars are often sold as farmers' 

 cider vinegars." 



Hop investigations {Oregon 8ta. Rpt. 191S-H, pp. 17, 18). — From a study 

 made of the chemical changes of hops due to treatment with sulphur dioxid 

 fumes the following conclusions are drawn: 



" There is nothing to indicate that sulphuring in the bleaching process affects 

 the bitter resins. The resin of the ' sulphured ' hop contains no sulphur. The 

 sulphur dioxid does not combine with the essential oil of the hop. The 

 * unsulphured ' hop contains .sulphur in the sulphate form, but no sulphur which 

 is volatile by the ordinary steam distillation. Different samples of ' sulphured' 

 hops contain different amounts of sulphur, both total and volatile with steam. 

 There seems to be no definite proportion between the volatile sulphur and the 

 total sulphur. The amount of sulphur present in the unsulphured Oregon hop 

 is practically constant. The analytical methods which have been in use for the 



