PRODUCTS DERIVED FROM TUKPKNTINES. 227 



CHAPTER IV.— MANUFA(JTURE OF THE VA- 

 RIOUS PRODUCTS DERIVED FROM 

 TURPENTINES. 



EvKET turpentine consists of an essential oil and of a solid sub- 

 stance (colophony) in solution in the oil. By distilling the oil at 

 a temperature of 158° C. (the boiling point of the oil), the colo- 

 phony or resin is left as a residue. 



The mode of distillation followed by the natives is a very pri- 

 mitive one. The apparatus employed is similar to that already 

 described in the preceding chapter. Not unfrequently no water 

 at all is used, so that the colophony gets more or less burnt, and 

 some acetic acid, alcohol, naphtha, and other impurities are pro- 

 duced and distil over with the oil. 



A great improvement on this rude mode of distillation is easily 

 effected with apparatus of almost equal simplicity and of scarcely 

 higher cost. The crude resin should first be raised to a tempera- 

 ture just high enough to liquefy it, and passed through a sieve to 

 free it from pieces of bark and other impurities. It should then 

 be run into the boiler of a still, heat being applied, either by an 

 ordinary furnace or a steam-jacket, until the mass attains a uni- 

 form temperature of 100° to 158°. This temperature should be 

 continued until the accidental water contained in the oleo-resin has 

 been driven off, together with pyroligneous acid, ether, and methy- 

 lic alcohol. A thin stream of water should now be admitted, so 

 that the temperature may be kept at or below 158°- The distilla- 

 tion will continue, water and turpentine oil passing over into a 

 receiver fitted with two taps, one at the bottom, the other higher 

 up ; the water is drawn off from the former, the oil from the lat- 

 ter. The progress of the distillation should be judged by means 

 of samples taken at intervals in a graduated measure. When the 

 distillate shows only a very small percentage of oil, the still-cap 

 should be removed, and the hot liquid rosin or colophony drawn 

 off by a tap near the bottom of the boiler and at once run through 



