56 BULLETIN 1003 U. S. DEPARTMENT OF AGRICULTURE. 



engage in the production of flotation oils from resinous wood wastes 

 in the Northwest. A list of uncompounded pine oils and other dis- 

 tilled wood products used, either alone or for producing blended oils 

 for flotation, is given herewith. Some idea of the required proper- 

 ties may be derived from the specific gravities : 



Crude pine oil. Pine-tar oil, double refined (sp. gr., 



Crude wood turpentine. 0.965 to 0.990). 



Pine oil, steam distilled (sp. gr., 0.925 Pine tar, thin (sp. gr., 0.980 to 1,000). 



to 0.940). Wood (pine) creosote, refined. 



Pine oil, destructively distilled. . Hardwood oil (Michigan) (sp. gr., 



Pine- wood oil (light) (sp. gr., 0.950). 0.960 to 0.990). 



Pine-wood oil (heavy) (sp. gr., 1.025). Hardwood oil (Michigan) (sp. gr., 



Pine-tar oil (sp. gr., 1.025 to 1.035). 1.06 to 1.08). 



REFINING CRUDE WOOD TURPENTINE. 



The crude wood turpentine is a complex mixture of oils, both 

 lighter and heavier than pinene, certain of which impart to the tur- 

 pentine an objectionable, penetrating odor and dark color, from 

 which wood turpentine having the accepted commercial require- 

 ments, and of uniform quality, is to be obtained. To compare favor- 

 ably with gum spirits the refined product should, in addition to its 

 odor and color, have a correspondingly narrow boiling-point range 

 or distillation-temperature limits. 



In refining crude wood turpentine it is customary to subject it to 

 steam distillation, after thorough mixing with caustic alkali to re- 

 move or hold back certain constituents, whereby it is separated into 

 a fraction lighter than turpentine, having a yellow color and pene- 

 trating odor, a turpentine fraction, and a pine-oil fraction. The de- 

 tails of operation and the proportion and quality of the products 

 thus obtained vary greatly with the quality of the crude oil, as well 

 as with the care observed in dividing or cutting the fractions. In 

 doing this the still operator is commonly guided by the density, odor, 

 color, etc., of the oil in changing over from one fraction to another, 

 which is not conducive to uniformity of results. This insufficient 

 standardization of the product has contributed materially to the un- 

 favorable attitude of consumers toward wood turpentine, as well 

 as to the lower price commanded by and greater difficulty in market- 

 ing this product as compared with gum spirits. 



The necessity of separating a light fraction that must be marketed 

 as an inferior turpentine or special product because of its objection- 

 able odor and color, moreover, is a wasteful practice, in that this 

 product is made up largely of pinene which properly belongs in the 

 turpentine fraction. Owing further to imperfect fractionation, or 

 the tendency of the heavier oils to pass over with the turpentine, 

 only in part overcome by the use of column stills, a considerable 



