140 , VARIETIES OF CATECHU. 
ART. XXXVIL— CONTRIBUTIONS TO THE CHEMISTRY OF THE 
VARIETIES OF THE CATECHU. 
By Prof. Delffs. 
Along with the Bengal catechu, which forms dark red- 
dish-brown cakes scattered'overgWith the husks of rice, there 
now occurs pretty frequently in commerce, the so-called 
Bombay catechu, in large irregular pieces of a uniform 
blackish-brown colour and fatty lustre, and which contain 
leaves of a species of palm disseminated through their mass. 
As both kinds are derived from Jlcacia Catechu, the dif- 
ference between them must be owing to the mode of treating 
them on evaporation ; perhaps the last kind has been some- 
what burned. The catechu in square pieces has been re- 
jected by the Prussian and also by.the Baden Pharmacopoeia, 
as an artificial product, consisting of clay and some as- 
tringent extract, while it has been admitted by the Ham- 
burg Pharmacopoeia. The author has never been able to 
discover any considerable amount of aiumina'iin it ; moreover 
the same kind still occurs in commerce, only that the squares 
are caked together ; but it agrees with the old article in its 
lower specific gravity, ready friability, and sparing solu- 
bility in water. 
When Bengal catechu is treated in a displacement-ap- 
paratus with ordinary ether containing water, and the 
liquid which passes (which does not separate into two lay- 
ers, as with galls,) is evaporated under the air-pump, a thick 
yellow syrup is obtained, and subsequently a brittle, yel- 
lowish, shining, amorphous mass of catechu-tannic acid, 
which tenaciously retains a little of the ether. It readily 
absorbs so much moisture from the air as to deliquesce into 
a yellow syrup. Its aqueous solution yields with bichro- 
mate of potash a considerable brown precipitate, which 
does not dissolve in muriatic acid. The alkaline salts of the 
