on some n.s.w. tan-substances. 265 



Standardisation of Permanganate. 

 20 c.c. indigo. 



M 16-9 c.c. KMn0 4 required. 



20 c.c. indigo. 



10 c.c. decoction (1 grm. to 1 litre). 



P 25-7 KMnO, required 1st test. 



Q 25-8 do. 2nd do. 



R 25*75 do. for 10 c.c. decoction - 16-9 



8-85 K 



Decoction steeped in hide powder. 

 Filter. 



10 c.c. of the nitrate. 

 20 c.c. indigo. 



S 17*3 K Mn O 4 required 1 st test. 



T 174 do. 2nd do. 



U. 17-35= do. for 10 c.c. filtrate - 16-9 



•45 Y. 



8-85 - -45 = 8-40 W. 



Now the percentage of moisture in the tannic acid = 10 '4 (by 

 actual experiment). 



.-. "We have 84 x _100 = 9-375 



Now 9-375 x 1-05 (Schroeder's factor, see p. 266) = 9-8438 

 = our permanganate value of Schering's gallo-tannic acid. 



Particulars of Substance — Schering's gallo-tannic acid ; infusion 

 made 13th August, 1888 ; examined for tannin 14th 

 August, 1888. 



The whole of the operations already described, in which the 

 decoction is used, must be repeated, with substitution of Schering's 

 tannic acid, 1 gramme to the litre of water, for the decoction. 



