86 



EEPOET OF CHEMICAL LABOEATOBY 



L'ses of the 

 juice for 

 niaking an 

 intoxicating 

 liquor 



the latex itself may be expected to furnish valuable evidence as to the precise nature 

 of the toxic principles of the plant. It is worthy of note that experiments carried out in 

 India' indicate that, while the fresh leaves are extremely acrid, producing severe vomiting 

 accompanied by much pain and distress, the cooked leaves are innocuous, and the writer 

 has observed goats and sheep eating witliered parts of the plant, while the natives aflSrm 

 that they will not touch the fresh plant. 



The milky juice of G. procera is undoubtedly used in the preparation of an intoxicating 

 liquor, both in India and in Central .\frica, but it is impossible to gather whether the juice 

 itself is directly fermented or is simply used as a ferment or bitter. Sir G. Birdwood 

 {Bomh. Prod., 208) says, " the intoxicating liquor bar is prepared from it by the tribes 

 of the Western Ghats," and Lisboa, in Usefnl Plants of Bomharj, asserts that the tribes 

 of C'eiitral Africa prepare from it their ;/n/'v. 



Details 

 of the 

 reaction 



A Colour Eeaction for the Latb.x of CALOTRons Peocera 



When the latex is diluted with four volumes of water, and a few drops of acetic 

 acid added, and the liquid boiled, coagulation readily takes place, and by straining off 

 the coagulated gutta-percha and filtering, a clear, pale yellow liquid, of decidedly acid 

 reaction to litmus, is obtained. To this liquid, and to the residue left on its evaporation, 

 were applied the customary reagents giving colour reactions. Those having strong 

 sulphuric acid as a basis — Erdmann's, Frohde's, Buckingham's, Mandelin's, etc. — were 

 found to give, with the liquid, green to blue colorations ; of the many others tried, none 

 gave any reaction worthy of note. When sulphuric acid, diluted with one half its volume 

 of water to prevent charring, is carefully added to the liquid, a greenish-blue ring is formed, 

 and, on carefully mixing the liquids, a bluish-green solution results. The addition of traces 

 of oxidising agents causes a change of colour to a deep Prussian blue. Ferric chloride 

 has been found the most suitable oxidiser, the blue colour produced in its presence being 

 comparatively stable, lasting for two or three hours, and then changing slowly to a dark 

 brownish-purple. The more energetic action of such oxidisers as hydrogen peroxide, 

 nitric acid, chromic acid, and sodium persulphate, even when these are present only 

 in minute traces, results in a quick change of the blue colour to dark green, then greenish- 

 brown and finally deep yellow. In the presence of nitrates the blue colour rapidly changes, 

 owing to the formation of nitric acid, while the presence of nitrites prevents its production, 

 the deep yellow colour being at once developed. 



The reagent found to give the most satisfactory results is prepared by diluting 

 sulphuric acid with one half its volume of water, and adding sufficient ferric chloride 

 to impart a faint yellow colour to the liquid. A mere trace of ferric chloride is not 

 sufficient to develop the blue colour ; on the other hand, excess is to be avoided, as any 

 marked yellow colour of the reagent would interfere. The reagent is added carefully 

 in equal volume to the liquid to be tested; a deep blue ring forms at the junction of 

 the liquids, and, on mixing, a deep Prussian blue colour is developed. A decided blue colour 

 is given by the reagent to 1 c.c. of a liquid containing one i)art of latex in 250 parts. 

 Sulphuric acid alone gives no coloration when added to a latex solution of this strength, 

 but the subsequent addition of a drop of ferric chloride solution brings up the blue colour. 



The substance which gives rise to the blue colour on the addition of sulphuric acid 

 and an oxidising agent, appears to be present in the latex in very minute quantity, and 

 has not yet been isolated. The following facts regarding its properties have, however, 

 ' Harvey, Report on ifalico-lajal Jtdunis, Bengal Presidency, 1870-1872 



