368 ESTIMATION OF TANNIN" 



Wild Cashew Bark. — Infused 100 grs. in cold water for 24 hours, 

 and made up the infusion to measure exactly 8,000 grs. : 2,000 grs. of the 

 infusion required 180 grs. of a standard solution of gelatine (1,425 grs. 

 gelatine solution = 5 grs. of tannin) to precipitate the tannin = *630 gr. of 

 tannin = 2"52 per cent, of tannin. 



Po-Ca-De Bark. — Infused 100 grs. in cold water for 24 hours, and 

 made up the infusion as before to 8,000 grs. : 2,000 grs. of the infusion 

 required 405 grs. of a standard solution of gelatine (1,388 grs. of gelatine 

 solution = 5 grs. of tannin) to precipitate the tannin = 1*455 grs. of 

 tannin = 5 - 82 per cent, of tannin. 



Sirada Bark. — Infused 100 grs. in cold water for 24 hours, and made 

 up the infusion as before to 8,000 grs. : 3,000 grs. of the infusion required 

 325 grs. of gelatine solution (1,388 grs. of gelatine solution = 5 grs. of 

 tannin) to precipitate the tannin = 1*170 grs. of tannin = 3*12 per cent, 

 of tannin. 



Hetchia Bark. — Infused 100 grs. in cold water for 24 hours, and made 

 up the infusion as before to 8,000 grs. : 3,000 grs. of the infusion required 

 250 grs. gelatine solution (1,388 grs. gelatine solution = 5 grs. tannin) to 

 precipitate the tannin = *81 gr. of tannin = 2*16 per cent, of tannin. 



Horahe Bark. — Infused 100 grs. in cold water for 24 hours, and made 

 up the infusion as before to 8,000 grs. : 3,000 grs. of the infusion required 

 500 grs. of a standard solution of gelatine (1,447 grs. of gelatine solution 

 == 5 grs. tannin) to precipitate the tannin == 1727 grs. tannin =4*6 per 

 cent, of tannin. 



Warahcah Bark. — Infused 100 grs. in cold water for 24 hours, and 

 made up the infusion as before to 8,000 grs. : 3,000 grs. of the infusion 

 required 400 grs. of a standard solution of gelatine (1,447 grs. gelatine 

 solution = 5 grs. tannin) . to precipitate the tannin = 1*38 grs. tannin 

 = 3*68 per cent, tannin. 



Mora Bark {Mora excelsa). — Infused 100 grs. in cold water for 24 

 hours, and made up the infusion as before to 6,000 grs. : 3,000 grs. of the 

 infusion required 290 grs. of a standard solution of gelatine (1,399 grs. 

 gelatine solution = 5 grs. tannin) to precipitate the tannin = 1*037 grs. 

 tannin = 2*074 per cent, tannin. 



The following is a summary statement of the per-centages of tannin in 

 the barks examined : — 



Wild Cashew - 2*52 per cent. 



Po-Ca-De - - - - - 5-82 

 Sirada ----- 3"12 



Hetchia - - - - 2-16 



Horahe - 4-60 



Waramcah - - - - - 3-68 



Mora - - - - - 2-13 



The quantity of tannin contained in the specimens examined is far too 

 small to admit of the barks being successfully used as tanning materials, 



