380 Scientific Intelligence. 



Examination of the Rind of the Mangosteen (Garcinia Mangostana)^ 

 By Dr Schmid. 



The rind was first boiled with water, which extracted tannin. The re- 

 sidue was then treated with hot alcohol ; the filtered fluid deposited a 

 resinous substance, which is a mixture of a resin and a crystalline mat- 

 ter, which the author calls mangostine. To separate it from the resin 

 water is added to the hot alcoholic solution until it becomes muddy ; on 

 cooling the resin is deposited, and after standing for some the mangostine 

 is deposited in silky plates, which are further purified by precipitating 

 with basic acid of lead and decomposing the precipitate with sulphuretted 

 hydrogen, and repeatedly crystallizing the product from alcohol. 



Mangostine crystallizes in golden-yellow glittering plates without smell 

 or taste, fusible about 374° into a yellow fluid, which solidifies into an 

 amorphous mass ; by farther heating it is decomposed, a small portion 

 only subliming unchanged. It is insoluble in water, soluble in alcohol or 

 ether, and the solutions are without action on litmus. It dissolves in the 

 alkalies with a yellow or brown colour, nitric acid gives oxalic acid when 

 boiled with it, and sulphuric acid dissolves it with a yellow colour, pro- 

 ducing a partial decomposition. It is not precipitated by any of the me- 

 tallic salts except subacetate of lead. Chloride of iron gives a dark 

 blackish-green coloration. Its analysis gave results agreeing with the 

 formula C 40 H 22 O 10 . The lead compound was not obtained of constant 

 composition. The author refers to the probable relations of this sub- 

 stance to the resin of gamboge, which has the formula C 40 H 18 O 21 , and 

 Purcee or Indian yellow, said to be produced from the urine of camels 

 which have been fed on the fruits of Mangostana manganifer, of which 

 the formula is C 40 H 16 O 21 . He finds that euxanthic acid is a coupled 

 compound decomposed by sulphuric acid into euxanthine and a substance 

 which reduces oxide of copper. — (Annalen der Chemie und Pharmacie, 

 vol. xciii. p. 83.) 



BOTANY. 



Gutta Percha of Singapore. — " Of the gutta percha very small quan- 

 tities are now brought to Singapore ; it has become a manufactured sub- 

 stance. A vast variety of its gum, at various prices, from three to thirty 

 dollars a picul, is brought in by the natives. Some of these are deep red, 

 some quite white, and many of them are hardly coherent, breaking down 

 and crumbling between the fingers. These are cut and broken up, and 

 cleared from the scraps of bark and wood which are generally found among 

 them ; they are then boiled in an iron pan with coco-nut oil, and stirred 

 until thoroughly amalgamated. This mixture is allowed to cool again, 

 when it is broken up and re-boiled with more oil, sometimes as often as 

 four times, or until the mass acquires a certain tenacity. The good gutta 

 percha, sliced into thin shavings, is then added in greater or less propor- 

 tion, according to the quality of the basis, and the whole well mixed. 

 The Chinese who do this are very skilful, and manage to produce from 

 a great variety of gums a very uniform article, — wonderfully so, when it 

 is considered that the gum is bought by the merchants in very small 



quantities at a time as the natives bring it in There seems to be 



a great mystery about the Gutta Percha trees. I was in the heart of their 

 country, and yet could get nobody to show me a single tree. I think the 

 fact is, that they have all been long ago cut down within any reasonable 

 distance of the settlements. I saw large quantities of the gum, though 

 none of the best quality, on the Indragiri. I think I can distinguish at 

 least five sorts, which are probably the produce of different trees ; or 

 rather five classes of gums, for perhaps the species are many more, and 

 yet, though I offered great inducements, I could not get even a leaf. Of 



