CHEMISTRY. 461 



ceut acetic acid. This was heated fioui 1 to 2 hours at 100"^ in the 

 water bath, '20 ec. of boiliiiy water added, the osazoiie coHected on a 

 tared lilter which had been previously moistened with boiling- water, 

 washed with GO to 100 ce. of boiling water, and dried at 105 to 110° 

 for 3 hours. 



The experiments with sucrose showed that the acetic acid failed to 

 cause complete inversion, and in the subsequent experiments the 

 sucrose was therefore inverted with hydrochloric acid, the acid neu- 

 tralized with sodium acetate, the solution made up to 20 cc. and 

 treated as before. In the presence of maltose the sokition was 

 heated 1.5 hours. This sugar increases the yield of dextrosazone 

 slightly. When dextrin (achroo dextrin) is present 1.5 hours are insuf- 

 ficient to obtain the maximum yield of dextrOvSazone, and the solution 

 must be heated L* hours. Dextrin also increases the amount of osazone 

 obtained. 



The results are important, as they point a method of deternuning 

 dextrose in the presence of maltose, isomaltose, and dextrins. The solu- 

 tion should not contain more than 0.2 gm. dextrose in 20 cc. One 

 gram each of plienylhydrazin and 50 per cent acetic acid must be 

 added and the solution heated 1.5 hours, 2 hours when dextrins are 

 present. The osazone is washed with 60 to 80 cc. water and dried on 

 a tared filter for 3 hours. Factor: 1 osazone=l dextrose, in the pres- 

 ence of maltose and dextrin 1 osazoue=1.04: dextrose. The factor for 

 levulose under similar conditions is 1:1.13. Sucrose must be pre- 

 viously inverted; factor: 1 sucrose = 1.33 osazone. — w. ii. krug. 



On the determination and the changes of hop tannin, and on 

 the action of the hop tannin during the preparation of •wort, 

 J. Heron {Jour. Fed. In.st. Brewing {189G), p. 10:2; abs. in Wocheuschr. 

 Brauerei, 13, p. 497; and in Chem. Centhl., 1896, II, Fo. 3, p. 136).— Ten 

 grams of ho])S are i)laced in a flask marked at 1,005 cc. and shaken with 

 900 cc. of boiling water, digested on the water bath for 1 hour with 

 occasional shaking, made up to the mark at 15.5°, well mixed and fil- 

 tered as clear as i)ossible; 100 cc. of the filtrate corresponds to 1 gm. 

 of hops. 



The following reagents are required for the determination : (1) Potas- 

 sium permanganate solution containing 1 gm. per liter and standardized 

 with deci-normal oxalic acid, 10 cc. of the latter recpiiring 31.G cc. of the 

 permanganate solution. (2) Indigo solution made by dissolving 5 gm. 

 of the best indigo-carnune in 500 cc. of water, adding 50 cc. concentrated 

 sulphuric acid, and diluting to 1 liter; 20 cc. of this solution should 

 recjuire 20 cc. of the above permanganate solution. (3) Gelatin solu- 

 tion; 25 gm. of ]SIelson gelatin are softened in 250 cc. of water for C 

 hours, brought into vsolution by heating on the water bath, saturated 

 with salt, made to a liter with saturated salt solution, well shaken, and 

 filtered after standing for several days. (4) Dilute sulphuric acid, con- 

 taining 50 cc. concentrated acid per liter. 



