SUMMARY. 35 



French and American turpentines consist largely of ovpinene 

 and 95 per cent of the fresh oils will generally distill below 170. 

 The oil of lodgepole pine consists of the unstable terpene phellandrene, 

 and has a higher boiling point than ordinary turpentine. The oil 

 from the sugar pine consists mainly of or-pinene, but contains 

 about 25 per cent of high-boiling constituents, a portion of which 

 is a sesquiterpene. However, because there is an extremely small 

 flow of "gum" from the sugar and lodgepole pines their volatile 

 oils will hardly become commercial products. 



The oil from the western yellow pine from California distills largely 

 between 168 and 172 and consists mainly of /?-pinene. The 

 latter is a normal constituent of "gum" turpentine and invariably 

 accompanies <*-pinene in nature. Of all the oils examined, that 

 from the western yellow pine from Arizona conforms most nearly to 

 ordinary turpentine. It consists largely of or-pinene with but 

 small amounts of /?-pinene and limonene. There is no reason to 

 suppose that both the California and Arizona oils will not serve the 

 purposes for which ordinary turpentine is commonly used. Prac- 

 tical tests are necessary, however, to determine this point. In addi- 

 tion to its solvent properties the chief function of or-pinene in 

 turpentine is usually considered to be that of absorbing oxygen and 

 hence promoting the drying of paints and varnishes. Whether it 

 really has a "drying" effect has been often disputed. 1 Samples of 

 the oil from California western yellow pine, when exposed to the 

 light in glass vessels stoppered with corks, soon became yellow and 

 resinous. Experiments performed by Prof. E. Kremers, of the 

 University of Wisconsin, showed that limonene absorbed oxygen 

 fully as rapidly as pinene. It would seem, therefore, that other 

 terpenes have as great an affinity for oxygen as or-puiene, and 

 their solvent power is fully as great. 



By redistilling the volatile oil from pinon pine to remove the 

 cadinene 75 to 80 per cent of oil could be collected up to 175; 

 this distillate would consist almost entirely of a-pinene and 

 /?-pinene, and would be very similar to ordinary turpentine. How- 

 ever, the distillate retains in part the characteristic odor of the 

 cadinene residue and this odor might prove objectionable to the 

 user. 



The volatile oil of digger pine is not at all similar to ordinary 

 turpentine oils and consequently can not be used for the same pur- 

 pose. It consists almost entirely of heptane of uniform specific 

 gravity and boiling point. It is readily purified by agitation with 

 a small amount of concentrated sulphuric acid. Various industries 

 should find in this a cheap and valuable solvent where uniformity 

 is required. 



i Compare Powney, "The influence of solvents on the drying of linseed oil," Analyst, pp. 192-198, vol. 

 35, 1910. 



