VALUE OF OAK LEAVES FOR FORAGE. 



17 



appeared inexplicably high. The only possible explanation seemed to 

 be that the tannin content, which, by the method of difference, falls 

 in this group, had not been accounted for. It was necessary, then, to 

 make determinations of tannin. 



In determining the tannin, the method of Giinther was followed ; that 

 is, two grams of the substance to be analyzed was taken and the tannin 

 extracted with hot water, in which it is easily soluble, until a dilution 

 of 1 to 400 parts was obtained. This dilution is necessary in order that 

 potassium permanganate may completely oxidize tannin in the presence 

 of indigo-carmine. The oxidizing power of the indigo-carmine was 

 determined by extracting all the tannin by means of animal charcoal 

 and titrating with potassium permanganate. The difference between the 

 two titrations was the tannin oxidized by the potassium permanganate. 



With these exceptions in the ether extract and the nitrogen-free 

 extract, the regular official method was followed; and the /table below 

 gives the results of the analyses of the different species of pak in an air- 

 dry condition. As a means of exact comparison, these results were cal- 

 culated first to a water-free basis, and finally, to an alfalfa hay basis. 

 The analyses were all carried out in duplicate and the averages found 



as follows: 



ANALYSES OF OAK LEAVBS. 



Samples Air Dry. 



Water-Free. 



