NOTES ON TANNING SUBSTANCES. 297 



Acacia dealbata (Silver Wattle) bark is used in Tasmania, where the 

 tree abounds from the level of the sea to nearly 2,000 feet, growing vigor- 

 ously in great extremes of temperature, even where the mercury indicates 

 21 deg. at sunrise. It is evergreen, and would probably succeed well in the 

 South of England. It grows from 80 to 120 feet high, and measures from 

 5 to 9 feet in circumference at four feet from the ground. 



Acacia melanoxylon (Blackwood). — The bark of this tree is used for 

 tanning ; it is an abundant timber tree in Tasmania, about 150 feet high. 



The bark of Acacia mollissima (Black Wattle) is also used for tanning 

 there. These trees were first called wattles from being used in the early 

 days of the colony for forming a network or wattling of the supple twigs, for 

 the reception of the plaster in the partitions of houses. 



Mimosa Bark. — A considerable quantity of acacia bark, known in the 

 trade as mimosa bark, is imported for tanning. It is brought chiefly from 

 Tasmania and Australia. It is very hard, and difficult to grind fine. The 

 tannin is not so easily extracted as from other barks. It also deposits no 

 " bloom," and, generally speaking, is not much liked by English tanners, it 

 being chiefly used where a red leather is required. 



Gambier. — The astringent substance known as gambier (or terra 

 japonica — so called from being at one time supposed to be an earth) is pro- 

 duced by boiling and evaporating the bark and wood of Uncaria Gambir. 

 When the evaporated juice has acquired a proper consistency, the liquor 

 is strained, and soon coagrdates into a mass. It is then dried in the sun, 

 and packed in bales or cakes of different sizes. It is frequently mixed 

 with sand or other impurities ; has little smell, but a sweet astringent taste 

 in the mouth, and is gritty. If it is perfectly' pure, it will totally dissolve 

 in water ; otherwise the impurities will remain behind. It is sometimes 

 met with of a pale reddish brown, of a dark blackish brown, or a black 

 like bitumen. 



There are different varieties, called catechu, cutch, and kassu, from India. 

 Dr Hooker, in his Himalayan Journal, states — " This province (Soan Valley) 

 is famous for the quantity of catechu its dry forests yield ; the plant 

 (Acacia Catechu) is a little thorny tree, erect, and bearing a rounded head 

 of well-remembered prickly branches. Its wood is yellow, with a dark 

 brick-red heart, most profitable in January and useless in June for yielding 

 the extract." 



Gambier is chiefly used in England, mixed with bark and valonea, for 

 tanning kips for upper leather ; but it is not a good material for tanning sole 

 leather, merely tanning the hide, without filling up the pores or making 

 a firm leather. Gambier is also used by dyers and curriers. The Indians 

 chew catechu with the betel-nut. In 1856 the imports of gambier 

 amounted to 6,847 tons. In the past three years the imports into the 

 United Kingdom averaged 9,200 tons, and of catechu nearly 3,000 tons. 



Algarobilla. — The seed-pocls of this tree (Prosopis pallida), which 

 grows in South America, contain a very large percentage of tannin, and are 

 used in Valparaiso and other places for tanning. A few years ago, about 



