56 



WILLIAMS. 



sterling per ton. Freight charges to Australia from the Philippines are 

 also very much lower than they axe to the United States. I estimate 

 the cost per ton of dry bark, as follows : 



Pesos. 

 8.00 

 2.00 



Felling and stripping 

 Delivery at kilns 



Drying 

 Tax 



Freight (Australia) 



Total 



1.50 



3.00 



12.50 



27.00 



CUTOH MANUFACTURE. 



C'ntch is prepared by extracting the bark with water and evaporating 

 the liquor to a suitable percentage of moisture. Cutch prepared by the 

 best methods now in use has approximately the following composition 

 and characteristics : 



Per cent. 



Water 20 



Tannin 50 to 55 



"Insolubles" 



(Ash 



Nontans 



Sugars 

 Organic 

 Acids, etc. 



2 to 



5 



1 to 



2 



5 to 



7 



G to 



18 



■ The extract produces a reddish-browni leather, somewhat harsh and 

 thick-grained, due to the high astringency of the tannin; but it gives a 

 very satisfactory tannage vi^hen mixed with other materials.^* 



The tannin, coloring matter, "insolubles," and nontans, each plays a part in 

 the tanning process. Mangrove tannin is a "greening tannin" of the pyrocatechol 

 series. Its empirical formula is generally accepted as C24H,60i2. It is a deriv- 

 ative of the dihydroxy phenol catechol. Closely related to the tannin are the 

 red coloring matter and the insolubles. Nierenstein and Webster " express the 

 relationship by the equation: 



Mangrove tannin. 

 CX 



a Phlobaphene. 

 CO 



p Phlobaphene. 

 CO 



HOOC 



HOOC 



OH 



OH 



OH 



CO 



The more soluble, red colored substance is produced by oxidation, and this, 

 by the splitting off of water, forms the less soluble phlobaphene which constitutes 

 the bulk of the so-called "reds" which deposit as a slime upon cooling extract 

 liquors. It is certain in any case that the tannin is the source of the red 



"Collegium (1902), 322-324; Ibid. (1904), 15-16. Also Bull. Imp. Inst., Lon- 

 don (1904), 2, 163-166. 



"Nierenstein and Webster, Collegium, 1909, 337. 



