Catechu Is An Extract Of The Khair Tree Or Acacia Catechu Of Bombay

: ON THE SEMI-NEUTRAL, BROWN.

Bengal, and other parts of India. With the exception of such earthy

matters as are communicated to it during the preparation, or are added

purposely as adulterants, catechu is entirely soluble both in water and

alcohol. An aqueous solution has a reddish-brown colour, and gives the

following results:--protosalts of iron thrown down olive-brown and

persalts greenish-brown precipitates; salts of tin and lead yield

brownish-yellow and brick-coloured deposits respectively; while acetate

of copper or bichromate of potash furnishes brown residues. To our

knowledge, none of these have been introduced as pigments, but a brown

prepared by Dr. Lyon Playfair some years back from the catechu bark has

been described as exceedingly rich, transparent, and beautiful; and



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