LEGUMINOS^ PRODUCING TANNING MATTERS AND DYES 34 1 

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Caesalpinia brasiliensis (Tree.) — The wood of this tree is hard, 

 compact, and takes a polish. It is devoid of sap-wood, and when 

 freshly cut the colour of the wood is brick-red. The older the tree 

 the larger the amount of colouring principle. 



Caesalpinia Sappan (Climbing Shrub). — This plant grows in India, 

 China, Japan, Brazil, and to a certain extent in every part of the 

 Tropics where it has been introduced. It is a hard wood, dark red 

 in colour externally, and brighter internally. It is the palest of the 

 red woods ; it is chiefly used in India for dyeing cotton fabrics. If a 

 decoction of this wood be combined with ammonia a fine red colour is 

 obtained; with salts of iron it gives black, and with sulphate of copper, 

 alum, or cream of tartar a very lasting blue. 



Caesalpinia veslcarfa (Tree). — This is the red wood of Jamaica, 

 which also grows in Guiana, the east of Cuba, &c. The colour is 

 brown with darker transverse veins. Both this variety and the variety 

 Csesalpnia tinctoria offer resources to the dyer. 



Caesalpinia sp. (Tree). — A Colombian tree exported in blocks 

 known as bois de terre ferine. The interior of the wood is golden 

 yellow with concentric zones of reddisli-yellow which become darker 

 as they approach the centre from the periphery. 



Caesalpinia sepiarla (Tree). — The wood is rich m colouring matter 

 and is used in Gaudeloupe for dyeing red. 



Haematoxylon campechianum (Tree). — Campeachy wood derives its 

 name from Campeachy Bay. The tree is a native of Mexico. South 

 America, Jamaica, and especially the West Indies produce a consider- 

 able ciuantity. Nowadays, this plant may be said to occur throughout 

 the Tropics. 



H seniatoxylon campechianiini contains a colouring matter with a 

 definite composition, hsematin, or haematoxylin. (C^^H^^Og.) 



There is no colouring matter contained in the bark, and the sap- 

 wood, which is of no value, is separated from the heart-wood. When 

 the wood is freshly cut the colour is reddish-yellow; in contact with the 

 atmosphere it turns blackish-red. 



Several samples of logwood (heart-wood and sap-wood) have been 

 analysed at the Mauritius Agronomic Station, and the tannin content 

 has been found to be io"3 per cent. 



Logwood is one of those natural products which have survived the 

 competition of artificial colouring matters, and not a few factories in 

 France are occupied in preparing the extract. 



The hsematoxylin which is contained in the duramen of the Cam- 

 peachy tree is colourless, but becomes oxidized on exposure to the air, 

 forming hsematin. The haematin occurs in the wood, partly in the free 

 state, partly in the state of glucoside, that is to say, partly in the state 

 of a product which is hydrolyzed into glucose and another special 

 substance, which in this case is haematin. The decomposition of the 

 glucoside has therefore to be provoked, and this is brought about bj' 

 cutting up the wood in such a way as to allow of spontaneous 

 fermentation. 



