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In view of the increasing importance of the so-called wood turpentine, $ 

 as a result of the scarcity of genuine turpentine oil, the U. S. Department 

 of Agriculture has caused two of its chemists, Messrs. Veitch and Donk, 

 to report, in the detailed manner customary with this Department, upon 

 the present experience relating to the production, refining and uses of 

 wood turpentine 1 ). The report deals in the first place with the production 

 of the oil by the various processes in use: destructive distillation, 

 steam-distillation, and extraction with volatile and non-volatile solvents. 

 Of these, steam-distillation produces the most useful oil. The distillate 

 obtained by the destructive process, that is to say the fraction which 

 distils over up to 170° and which is also called "wood turpentine" is 

 quantitatively too small in comparison with the oils of higher b. p. 

 Moreover, it is much more difficult to remove the characteristic pine-tar 

 odour of this product by refining, than is the case with the oil obtained 

 by steam-distillation. The method of extracting with volatile solvents is 

 still in its infancy, but several plants use the method of extracting with 

 hot rosin at 200°, which extracts the oil from the chipped wood. The 

 rosin yields the oil to a current of superheated steam which is passed 

 through it, and is afterwards used again for extracting fresh batches of 

 wood. There is also a method of extracting the oil and resin from the 

 wood by boiling the latter with soda liquor and removing the oil from 

 the liquor with a steam-current before the rosin acids are precipitated; 

 the cellulose of the raw material being worked up for paper. Of course 

 the residual wood from the steam-distillation or the extraction with volatile 

 solvents can also be made into paper-pulp or used for dry distillation. 



Great importance is to be attached to the next process of purifying 

 and fractionating the crude distillate, for which purpose a column-still 

 either working intermittently or continuously, should be used. The dis- 

 tillate resulting from the destructive process is first freed from phenols 

 by means of alkali and then refined by steam-distillation. Generally 

 speaking, insufficient care is bestowed upon this work, and apparently 

 the distillate is not fractionated; hence "carbonisation wood turpentine" 

 is not to be regarded as a first-class product, owing to the considerable 

 proportion of high-boiling oils contained in it. The portions of this oil 

 which distil over between 80 and 154° closely resemble rosin spirits; the 

 fraction boiling between 154 and 180° constitutes the destructively-distilled 

 wood turpentine. It contains pinene, dipentene and other compounds which 

 also occur in part in rosin spirits. The higher-boiling oils, with b. p. ex* 

 ceeding 180°, are mixtures of pine-tar and rosin oils in indefinite proportions 

 and are used as greases and solvents, in the manufacture of printers' inks, 8jc. 

 The constitution of the crude product, of the steam-distillation of light wood 



*) Wood turpentine, its production, refining, properties, and uses. U. S. Dept. of Agri- 

 culture, Bur. of Chemistry, Bulletin No. 144, 1911. 



