EXPERIMENTS IN REFINING WOOD TURPENTINE. 33 



;he reiining still consists of at least 54 per cent oils, 90 per cent of those 

 >ils will distill below 170 C.; that when the distillate contains from 

 54 to 30 per cent of oils, the oil is a mixture of light and heavy oils, 

 which must be again distilled to separate the light oils distilling 

 jelow 170. When the distillate contains less than 30 per cent of 

 nls, it contains practically no oil distilling below 170. The specific 

 gravity of the oils bears a fairly close relation to the percentage of 

 jils in the steam distillate. When the percentage of oils in the dis- 

 tillate is 55 to 53, the specific gravity is 0.8634 to 0.8638; when the 

 percentage of oils is 30 to 27 the specific gravity is 0.8811 to 0.8868 

 'omitting one doubtful result). 



The data can not be employed to show definitely the comparative 

 efficiency of the column and pot stills in refining wood turpentine, 

 rhey do indicate, however, in a general way that the fractionation 

 is sharper and that the intermediate fraction of the fight and heavy 

 [>ils is smaller from the column than from the pot still. It will be 

 noted that in the earlier stages of the distillation from the column 

 still, the distillate contained from 54 to 65 per cent of oils, while the 

 listillate from the pot still contained only 54 per cent. This indi- 

 cates, as has been said, a much sharper separation on the part of the 

 column still during the first of the distillation. If the distillation 

 were stopped at any given point, say when the percentage of turpen- 

 /ine in the distillate was 50, the separation in the column still would 

 >e more complete and the turpentine from it would contain less 

 icavy oils than that from the pot still. It has been stated that 

 from the column still a middle fraction containing about 5 per cent 

 [>f the light oils that were in the crude oils is obtained. Calcula- 

 ions based on the rate of distilling indicate that the middle fraction 

 Tom the pot still contains from 10 to 16 per cent of the light oils pres- 

 ent in the crude oils, and that it is larger than the middle fraction 

 Tom the column stills. 



Experiments similar to the foregoing were also conducted with 

 destructively distilled turpentine, and results of the same general 

 nature as to the separation from the heavy oils, percentage of oils 

 in distillate, etc., were obtained. The stills used in this work became 

 unavailable at this time and therefore no effort was made to separate 

 the light oils, distilling below 150 C., other than to make three frac- 

 tions of the distillate. The first fraction should have contained the 

 ighter oils with but smaU proportions of turpentine, the second frac- 

 tion the wood turpentine, and the third the pine oils, or, more prop- 

 erly, the heavier constituents of rosin spirits. The separation between 

 the light oils and the turpentine was not at all sharp, and a single frac- 

 tionation in the column still did not give in any case a fraction which 

 contained all the light oils, with but minor percentages of turpentine. 



7085 Bull. 14411 3 



