56 WOOD TUKPENTINE. 



In these plants when smaller quantities of crude oils are to be 

 refined, the first cost of the columns and difficulties of control make 

 the use of two simpler stills advisable, a periodic column still for the 

 turpentine and a simple gooseneck still for the refining of the heavy 

 or pine oils. The same apparatus is suitable for the refining of the 

 oils obtained by the destructive processes. It is necessary to wash 

 these products with soda or lime, as has been pointed out, and also 

 to refractionate once, or even several times, the portions obtained 

 from the first or preh'minary fractionation. 



As long as the distillate contains only water and such oils as may 

 properly be termed wood turpentine the percentage of wood turpentine 

 in the distillate will be from 62 to 54 per cent and throughout nearly 

 the whole distillation this relation may exist. When large quantities 

 of pine oils begin to distill, however, the ratio of oil to water in the 

 distillate drops rapidly and the changing quantity of oil in the dis- 

 tillate, together with the speed with which the ratio of oil to water 

 changes, furnishes the best evidence of the nature of the distilling 

 oils. It has been observed in general that when a column still is 

 employed and the percentage of oils in the distillate decreases rapidly, 

 the oils may be mixed with the turpentine until the percentage of 

 oils in the final distillate falls to about 45 per cent. If a pot still is 

 employed the indications are that when the percentage of oil in the 

 distillate falls below 50 it should no longer be mixed with the turpen- 

 tine, since distillates containing less than these amounts no longer meet 

 the requirements for turpentine and should be run to another tank 

 until the percentage of oil in the distillate falls below 30 per cent, 

 when the distillate should be run into a third tank. The oils in the 

 third tank will consist of pine oils alone, while those in the second 

 tank will consist of a mixture of turpentine and pine oils and should 

 be again distilled, and the distillate run into tank 1 until the oil in 

 the distillate falls below 50 per cent, when the remainder is run into 

 tank 3 without further distillation. 



STANDARDS OF QUALITY. 



Since wood turpentine is used as a substitute for gum spirits of 

 turpentine, it should comply with the customary tests applied to 

 gum spirits to determine its suitability for this purpose and also 

 with specifications for gum spirits. 



Inasmuch as the highest grade of wood turpentine need not be 

 employed in certain kinds of work, several grades, each suitable for 

 a specific purpose, may be made. In this way users will be enabled 

 to buy economically such wood turpentine as is suitable for their 

 various purposes, the utilization of the heavier oils will be promoted, 

 and the less perfectly equipped and operated plants will be able to 

 find a market for their products. 



