258 
Journal of Agricultural Research voi. xxvi, no. 6 
gallotannic acid from which the gallic acid has been extracted with ether. 
Add 2 cc. of the color reagent to each tube, then io cc. of a 20 per cent 
solution of Na 2 C 0 3 ; dilute the contents to volume and allow to stand five 
minutes. Compare the colors and calculate the amount of tannin in 
the sample. 
Known amounts of tannin were carried through this procedure, and 
the color developed compared with the standard tannin solution was 
found to be very close to 100 per cent. If, however, gallic acid was 
present, it was not carried through quantitatively. 
Since 20 gm. samples were taken and the tannin was extracted with 
200 cc. of alcohol, 10 cc. of the filtrate represent the tannin extracted 
from 1 gm. of sample. 
The percentages of tannin in the sorghums determined by the fore¬ 
going method were found to be as follows: 
Variety of sorghum: Per cent - 
Dawn. o. 06 
Darso. .4 
White Kafir. Trace. 
Hagairi.15 
Black Amber.2 
African Millet.27 
Club Head Sorgo.16 
Orange Cane.5 
Broom Com.4 
Yellow Maize. Trace. 
White Maize. None. 
