240 LEGUMINOS^E. 



ElephantiiDi Correa, a spiny tree, 50 to 60 feet higli, of the order of 

 AurantiacecB, common throughout India from the hot valleys of the 

 Himalaya to Ceylon, and also found in Java. There exudes from its 

 bark abundance of gum, which appears not to be collected for exporta- 

 tion per se, but rather to be mixed indiscriminately with other gum, as 

 that of Acacia. 



Feronia gum sometimes forms small roundish transparent, almost 

 colourless tears, more frequently stalactitic or knobby masses, of a 

 brownish or reddish colour, more or less deep. In an authentic sample, 

 for which we are indebted to Dr. Thwaites of Ceylon, horn-shaped 

 pieces about ^ an inch thick and two inches long also occur. 



Dissolved in two parts of water, it affords an almost tasteless 

 mucilage, of much greater viscosity than that of gum arabic made in 

 the same proportions. The solution reddens litmus, and is precipitated 

 like gum arabic by alcohol, oxalate of ammonium, alkaline silicates, 

 perchloride of iron, but not by borax. Moreover, the solution of 

 Feronia gum is precipitated by neutral acetate of lead or caustic 

 baryta, but not by potash. If the solution is completely precipitated 

 by neutral acetate of lead, the residual liquid will be found to contain 

 a small quantity of a different gum, identical apparently with 

 gum arabic, inasmuch as it is not thrown down by acetate of 

 lead. If the lime is precipitated from the Feronia mucilage by 

 oxalate of potassium, the gum partially loses its solubility and forms a 

 turbid liquid. 



From the preceding experiments, it follows that a larger portion of 

 Feronia gum is by no means identical with gum arabic. The former, 

 when examined in a column of 50 mm. length, deviates the rays of 

 polarized light 0°'4 to the right, — not to the left as gum arabic. This 

 was, we believe, the first instance of a dextrogyre gum ; ^ Scheibler has 

 afterwards shown (1873) that there are also dextrogyre varieties among 

 the African gum from Sennar. Gum arabic may be combined with 

 oxide of lead ; the compound (arabate of lead) contains 306 per cent, 

 of oxide of lead, whereas the plumbic compound of Feronia gum, dried 

 at 110° C, yielded us only 14-76 per cent, of PbO. The formula 

 (.Qi2jj2iQn-^2pb + 2 (C^'H^O") supposes 14-2 per cent, of oxide of lead. 



Feronia gum repeatedly treated with fuming nitric acid produces 

 abundant crystals of mucic acid. We found our sample of the gum to 

 yield 17 per cent, of water, when dried at 110° C. It left 3'55 per cent, 

 of ash. 



CATECHU. 



Catechu nigrum; Black Catechu, Pegu Catechu, Cutch, Terra 

 Japonica ; F. Cachou, Gachou brun ou noir ; G. Catechu. 



Botanical Origin — The trees from which this drug is manufactured 

 are of two species, namely : — 



1. Acacia Catechu Willd. (Mimosa Catechu L. fil., M. Sundra 

 Roxb.2), a tree 30 to 40 feet high, with a short, not very straight trunk 



^ Fliickiger, Pharm. Joarn. x. (1869). gard Mimosa {Acacia) Sundra as distinct 

 C4l. from A. Catechu. — Fig. in Bentley and 



^ Some Indian botanists, asBeddome, re- Trimen, part 17. 



