30 WOOD TUBPENTINE. 



through the still previously used. The data in Table 7 show that a 

 second distillation gave a refined wood turpentine which complied 

 with the most exacting requirements as to uniformity, specific gravity, 

 and behavior on distillation; furthermore, the odor of this turpen- 

 tine is much milder than that of the original crude oils, resembling 

 quite closely that of gum spirits. 



Table 6 contains all of the complete results obtained on the samples 

 collected in the experiments in refining crude steam-distilled wood 

 turpentine. The table is arranged on the basis of the specific gravity 

 of the sample, that with the lowest gravity being entered first. From 

 this table the successive samples of any distillation may be readily 

 picked out. For instance 6A t and 6A 3 are the successive samples of 

 the first fraction of the distillation of the sixth barrel and 9B, and 



o 



9B 4 are the successive samples from the second or B fraction of the 

 distillation of the ninth barrel. 



From the nature of the experiments, all of the data can not be 

 strictly harmonious. Variations in atmospheric pressure occasion 

 differences in distilling temperatures. Variations in steam pressure 

 and volume occasion differences in distilling temperatures, and 

 within limits in specific gravity and behavior on redistillation. On 

 the whole, however, the data (see Tables 4 to 8) show that a low dis- 

 tilling temperature, specific gravity, and refractive index, together 

 with a high percentage of turpentine in the steam distillate, are char- 

 acteristic of turpentines of which 90 per cent distill below 170 C. It 

 will be seen, furthermore, that when the percentage of oils in the 

 distillate falls below 35 or 30 per cent these oils consist altogether 

 of the heavier ones which distill above 170 C. Therefore, the con- 

 clusion drawn from Table 7 is that when the distillate contains 55 

 per cent or more of oils, these will comply with the requirements for 

 a high-grade uniform wood turpentine, 90 per cent of which will 

 distill below 170 C. When from 55 per cent down to 30 per cent of 

 the distillate consists of oils, considerable quantities of light oils are 

 present and the oils must be redistilled with steam, probably only once 

 from a column still, to separate the light oils, which should, as before, 

 constitute 55 per cent of the distillate. That portion of the distillate 

 containing less than 30 per cent of oils contains only heavy oils, or 

 pine oils, and need not be again distilled to separate oils boiling below 

 170 C. To this portion may be added the oils constituting less than 

 55 per cent of the distillate, of the redistilled middle fraction, or, if 

 desired, this portion may be kept separate, as the oils are somewhat 

 lighter than the heavy oils from the first distillation. 



Table 8 contains the data concerning the several fractions obtained 

 in the different distillations of the crude oils. These data are of the 

 same general nature as those in Table 7. The temperature of distil- 

 lation, proportion of turpentine in the distillate, specific gravity, 



