386 



The general composition of the resin as first prepared from the oleo-resin 

 may be stated as follows : — 



Dundathic acid (CoiH-.-jOs') ... . ... = i6-o per cent. 



Dundatholic acid (Ci.iH.jijOg^ ... . - 73-2 ,, (about)- 



Neutral resins, bitter principle, (Sic. ... ... — io-8 „ 



Experimental. 

 The thick, cream-coloured, pasty mass readily formed a white emulsion 

 when stirred with warm water, but if sufficient water were added, it formed a milky 

 liquid, with small hmips of somewhat hardened resin suspended through it. It 

 was strongl}'' acid, and had a slightl}^ aromatic although sour odour, and was mostly 

 dissolved in excess of hot solution of carbonate of soda, but partly separated out 

 again on cooling ; although if sufficient water was added, the precipitated salt again 

 dissolved. 400 grams of the oleo-resin, as received, were made into a thin emulsion 

 by adding an equal amount of water ; this solution was then distilled by heating 

 directly, as b}' this method the material boiled more steadily, and was not projected 

 in such an objectionable manner as when steam was passed directly into it. Fresh 

 water was added from time to time, and the distillation continued until the distillate 

 became practicall}^ neutral, and no more oil came over — a result which took about 

 seven hours" to accomplish. A considerable layer of a colourless oil floated on the 

 surface of the acid water. As the oil came over, and the gum went into solution, 

 the resin separated in lumps and globular masses, floating in the aqueous liquid. 

 The resin was then allowed to cool and solidify in the flask, the aqueous portion 

 removed, and filtered as clear as possible. 



The Essential Oil. 



The oil floating on the acid distillate, when separated, measured 54 c.c, 

 equal to 11-64 jx'r cent, of the oleo-resin by weight, or about 14 per cent, by volume. 

 It soon obtained the characteristic odour of ordinary " oil of turpentine," although 

 at first it was slightly aromatic. It was water- white, and gave the following 



results : — 



Specific gravity at X5° C. ... ... ... - 0-8629 



Rotation a„ in loo-mm. tube ... .. -^ -|- 20-2° 



Refractive index at 16° C. ... ... — 1-4766 



30 c.c. of the oil were distilled under atmospheric pressure, when nothing came 

 over below 155° C. ; between 155° and 156° C, 53-3 per cent. distiUed ; and between 

 156° and 159° C, 33-3 per cent, more came over. The residue in the flask, 13-3 per 

 cent., was also determined. 



The first fraction had — 



Specific gravity at ].^° C. ... .. - 0-8625 



Rotation a„ ... ... ... ... = 4-14-4° 



Refractive index at 17° C. .. ... = i'4755 



