The younger leaves of the shrub are said to produce the whitest and best gambier; the older, a brown and inferior sort. There are other species of Nauclea indigenous to Singapore, but they do not produce any extract.
Dr. Bennett has particularised four qualities of gambier:—
1. Small round cakes, about the size of a small lozenge. Color pale, purplish, yellowish, white.
2. Cubes, in which shape it is principally imported into England, and square prisms, or oblong pieces.
3. Circular discs, or short cylindrical pieces.
4. Cubical amylaceous pieces, of a darker brown than the other kinds.
Gambier is one of the most powerful of the pure astringents.
The chief places of manufacture are Saik, Malacca, Singapore, and Rhio or Bintang. Bennett, in his "Wanderings," says there are 60,000 plantations of gambier on this island. After that of Rhio, the next best gambier is that of Lingin. That used by the Malays, with the leaves of betel, in the same manner as cutch in other parts of India, is the finest and whitest; the red being stronger tasted and rank, is exported to Batavia, China, and England, for the purposes of tanning and dyeing. It is frequently adulterated with sago powder, but it may be detected by solution in water.
Large quantities of gambier are imported, under the corrupted name of cutch, into Calcutta, from Pegu. The quantity of gambier produced in Rhio, by the Chinese settlers, amounts to about 4,600 tons a year, about 2,000 of which are exported for the consumption of Java, the rest being sent to Cochin-China and other neighbouring countries.
Two methods of obtaining gambier are described. One consists in boiling the leaves in water, and in inspissating the decoction; the other, which yields the best gambier, consists in infusing the leaves in warm water, by which a fecula is obtained, which is inspissated by the heat of the sun, and formed into cakes.