58 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. 



chanical agitation with a paddle-wheel stirring device was the first 

 resort. It was subsequently found, however, that heating over a 

 flame in a distilling flask fitted with return-flow condenser is equally 

 effective and much simpler in execution. This method of treatment 

 thoroughly emulsifies the oil and caustic solution, giving the intimacy 

 of contact desired, while the inverted condenser continually returns 

 the aldehyde bodies to the action of the alkali until they have been 

 changed to the nonvolatile products previously discussed. The in- 

 verted condenser is then replaced by a Hempel column and the con- 

 tents of the flask distilled with steam, yielding from the start a tur- 

 pentine of standard requirements. 



Steam distillation is admirably adapted to the production of tur- 

 pentine of uniform quality, because it affords a simple means of con- 

 trol, in that the ratio of oil to water in the distillate is an index of 

 the composition of the turpentine (12). This is a gradually dimin- 

 ishing ratio in proportion as the oil contains less pinene and corre- 

 spondingly more of the higher-boiling pine oils. For any observed 

 oil-to-water ratio, however, the turpentine has a definite composition, 

 as indicated by its density, refractive index, distillation-temperature 

 limit, etc. This, of course, follows from the law of relative vapor 

 pressure of immiscible liquids. Its application as a simple and re- 

 markably accurate means by which to judge the composition of the 

 turpentine at any time during the distillation, however, has not 

 been given the consideration it merits (12) as a means of standardiz- 

 ing the output of commercial plants. Properly used, the oil-to-water 

 ratio makes possible the production of turpentine having a constant, 

 predetermined composition, any consignment of which will be prac- 

 tically the same as a preceding or subsequent shipment. 



Following up preliminary observations, based on the considera- 

 tions set forth, a series of experiments was conducted to determine : 

 (a) The relative efficiency of caustic soda, carbonate of soda, and 

 milk of lime as refining agents; (b) the proportion of alkali to crude 

 oil and concentration of the alkali solution giving the best results; 

 (c) the time necessary for the reactions set up by the alkali treat- 

 ment to produce its full effect ; (d) the effect of drawing off the alkali 

 after treatment and washing the oil with water before distilling; 

 (e) the effect of passing a current of air through the oil during treat- 

 ment with alkali. 



In carrying out these experiments 500 cc., taken from a large com- 

 posite sample of crude western yellow-pine turpentine, were used in 

 each test. The turpentine fraction proper was continued to where 

 the ratio of oil to water was 4 to 6, beyond which the proportion 

 changes rapidly, and a second turpentine fraction collected hot \\ ecu 

 the 4 to 6 and 3 to 7 ratios. The distillation was continued for the 



