24 



WOOD TURPENTINE. 



heavier constituents thus carried over is primarily controlled by the 

 proportion in the liquid. T t is also greater the less the fractionating 

 effect in the still. Fractionation, within limits, is decreased by 

 increasing the velocity of the distilling vapors; that is, the more 

 rapid the distillation, the smaller the space above the liquid in the 

 still, and the smaller the opening to the condenser, the more of the 

 heavy constituents the distillate contains. As distillation proceeds, 

 the liquid in the still becomes richer in the heavier constituents and 

 the vapors arising from this liquid also contain a larger proportion 

 of these, although less than the remaining liquid, until finally all of the 



lighter constituents 

 are removed and the 

 distillate consists 

 wholly of the heav- 

 ier ones. That is, 

 in the distillation of 

 a crude turpentine 

 from a pot still, the 

 first part of the dis- 

 tillate is a fairly 

 light product, con- 

 taining relatively 

 small proportions of 

 heavy oils. This 

 first portion is fol- 

 lowed sooner or 

 later, depending on 

 the proportion of 

 ligJit oils in the 

 crude oil and the 

 speed of distilla- 

 tion, by a product 

 containing continu- 

 ally increasing pro- 

 portions of heavy oils, until at a certain point the product no longer 

 contains light oils but consists entirely of what may be called the light 

 pine oils mixed with small proportions of the heavy ones. As distilla- 

 tion progresses this product also gradually changes in composition and 

 the proportion of heavy pine oils becomes greater until they form the 

 entire distillate. For these reasons it is impossible to secure more 

 than an approximate separation of crude wood turpentine into its 

 several chief constituents by a single distillation from a pot still. It 

 is necessary to make several redistillations of each of the intermediate 

 fractions or portions which have been distilled between certain limits. 

 Directions for doing this most satisfactorily are given on page 55. 



FIG. 1. A simple periodic column still, with chambers containing 

 broken rock. 



