462 EXPERIMENT STATION RECORD. 



The titration is made with 50 cc. of the hop extract in a flat, 1-liter, 

 porcehiin casserole, 20 cc. indigo solution and 100 cc. Avater being added. 

 The permanganate solution is run in rapidly from a burette, the liquid 

 being constantly stirred. The end of the reaction is shown by the 

 color of the liquid changing from yellowish-green to golden yellow. 

 From the number of cubic centimeters of permanganate used the 

 amount absorbed by the indigo solution must be deducted, and the 

 result multiplied by 2 gives the total oxidizable substance in 100 cc. of 

 the extract. 



One hundred cubic centimeters of the extract is now placed in a 

 wide-necked flask, mixed with 100 cc. of the gelatin solution, well shaken, 

 50 cc. of dilute sul]>huric acid added, together with a teaspoonful of 

 kaolin, again thoroughly shaken, and Altered. One hundred cubic 

 centimeters of the filtrate is placed in a porcelain casserole, 20 cc. of 

 indigo solution and 500 cc. of water added, and the titration carried on 

 as before. The amount corresponding to the indigo solution used is 

 deducted, and the result multiplied by 2.5 gives the oxidizable sub- 

 stances not hop tannin ])resent in 100 cc. of the extract. 



To obtain comparable figures, the author expresses the amount of 

 permanganate use ] in terms of oxalic acid. The gelatin solution must 

 be tested with permanganate and the corresponding correction applied 

 whenever found necessary. 



CJtanges which the tcmnin undergoes during storage. — The author con- 

 firmed the well-known fact that the hop tannin decreases during 

 storage. This seems to be especially so during the first year, ^o sat- 

 isfactory method of preventing this is known at present, but the author 

 found that sulphured hops kept much better than the nnsulphured. 



The inflnence of the hop tannin on the wort. — The author showed by 

 experiments that the hop tannin does not precipitate a single soluble 

 proteid during boiling, but that it seems rather to form a soluble com- 

 pound with the peptones of the wort. He calls this soluble compound 

 tannopeptone. As this compound is not changed by fermentation, it 

 must be present in the finished beer, and the tannin in all normal hop 

 beers is therefore not present in the uncombined state. It is therefore 

 incorrect to assume the absence of tannin in a beer which, on the 

 addition of oak tannin, gives a precipitate. — w. H. KRi'G. 



Eighth annual convention of the German Agricultural Experi- 

 ment Stations [Landw. Vers. Stat., 47 {1896), JSfo. 2-3, pp. 145-253, 

 Jig. 1). — The eighth annual convention of this association was held at 

 Kiel, September 12, 13, and 14, 1895, F. Nobbe presiding. Fifty-one 

 members and visitors were in attendance. The following propositions 

 approved by the previous convention M^ero passed to the second reading 

 and adopted: In the valuation of feeding stuff's protein, tat, and carbo- 

 hydrates should stand in the ratio of 3:3:1; in control analyses phos- 

 phoric acid is to be determined by one of the old and well-tested 



