\ 



ANALYSIS, REFINING, AND COMPOSITION. 55 



presence of dipentene does not fully account for the difference in 

 odor between wood and gum turpentines. Refined turpentines 2 and 

 5, both of which contained considerable quantities of dipentene, re- 

 sembled gum turpentine in odor more than the products from No. 

 4, which was more nearly like gum turpentine in composition. It 

 seems likely, therefore, that the distinctive odor of many wood tur- 

 pentines is due to some material which occurs in so small a quantity 

 that its presence is not readily indicated in any other manner than 

 by the odor. The odor of a wood turpentine like No. 3 is probably 

 due to the presence of rosin spirits, as mentioned on page 5*3. 



EFFECT OF COMPOSITION ON" TECHNICAL PROPERTIES. 



The most valued properties of turpentine are usually considered to 

 be its volatility, its solvent power, and its " drying " properties. 



VOLATILITY. 



The volatility of wood turpentines as compared to gum turpentines 

 would probably not be greatly affected by the differences in compo- 

 sition. This property is measured, approximately, by the range of 

 boiling points of the various constituents. Large quantities of heavy 

 oils decrease volatility, but it is doubtful whether the effect of small 

 quantities, up to 10 per cent, would be noticeable in practice. 



SOLVENT PROPERTIES. 



It is likely that the solvent properties of dipentene are quite similar 

 to those of pinene, since these terpenes are so much alike in other 

 respects; the solvent properties of the other materials which do not 

 occur in gum turpentines, but which may be present in wood tur- 

 pentine are probably sufficiently similar so that the small proportion 

 of these which may be present does not appreciably affect the solvent 

 properties of the mixture. 



DRYING PROPERTIES. 



In drying properties dipentene is apparently equal to pinene, since 

 it has been found that the time required for drying a mixture of 

 dipentene and linseed oil is the same as for drying a similar mixture 

 of pinene and linseed oil. 1 In the case of the drying properties it is 

 not likely that small amounts of rosin spirits, light oils, or even heavy 

 oils, would greatly affect the industrial value of the turpentine. 

 Until further data are available on the relation between the compo- 

 sition and industrial value of turpentines, the differences in composi- 

 tion between wood and gum turpentine should not be considered as 

 necessary indications of corresponding differences in value. 



1 This was determined by Edward Krerners, of the University of Wisconsin, in an in- 

 vestigation of terpenes as oxygen conveyors. 



