THE OPTICAL ROTATION OF SPIRITS OF TURPENTINE* 
BY CHAS. H. HERTY 
Among the physical properties of spirits of turpentine, none 
has proved of more interest than its optical rotation. In most 
specimens this property is very marked, and as the liquid is color- 
less and the determination readily made, many data are found on 
this subject in chemical literature. Slight variations in the rota- 
tion of different samples are to be expected, as spirits of turpen- 
tine is not a chemical compound but a mixture of substances, 
chiefly terpen es. From the results of numerous observations upon 
commercial samples, the view commonly held previous to 1891 
was that French spirits of turpentine, distilled from the oleoresin 
of Pinus maritima , is levo-rotatory and that American spirits of 
turpentine, distilled in years past, almost wholy from Pinus palus - 
tres , is dextro-rotatory. The difference in the character of the 
rotation was ascribed, therefore, to the different species from which 
the spirits of turpentine was produced. 
Recognizing the fact that American spirits of turpentine is dis- 
tilled from more than one species of pine, J. H. Long, 1 in 1891, 
undertook a study of the volatile oils distilled from oleoresins of 
well identified individual trees, these trees embracing the several 
species of pines subjected to turpentining in our southern states. 
He found that specimens from Pinus palustris (Long Leaf Pine) 
gave dextro-rotatory oils, while those from Pinus heterophylla 
(Cuban or Slash Pine) gave levo-rotatory oils. Since the oleore- 
sins from these two species are indiscriminately mixed, at the 
time of collection in the woods, the rotation of the oil distilled 
from such a mixture would naturally vary. Pinus palustris is the 
♦Reprinted from the Journal of the American Chemical Society, vol. 30, 
p. 863. 
!/. Anal. Appl. Chem., 6, 1. 
19081 
87 
