596 CONSIDERATION OF CARBON COMPOUNDS. 



stituents ; as many as seventeen having been found in one sample. Besides 

 three different terpenes and one sesquiterpene, were found acetaldehyde, acetic 

 acid, isovalerianic acid, amyl alcohol, menthol, menthon, C 10 H 18 0, menthyl 

 acetate, C 10 H 19 O.C 3 H 3 0, and others. 



Terpenes, C 10 H 16 . The terpenes are widely distributed in the 

 vegetable kingdom, especially in the coniferse and varieties of citrus, 

 etc., and are found in the volatile oils obtained from the individual 

 plants. The terpenes are readily acted upon by many agents and 

 hence undergo numerous changes. One of these changes is polym- 

 erization i. e., conversion into compounds of the composition C^H^ 

 and CjjoHgg, which may be effected by heating a terpene in a sealed 

 tube, or by shaking it with concentrated sulphuric acid or with cer- 

 tain other substances. Many of them also show a great tendency to 

 pass into more stable isomers under certain conditions i. e., when 

 acted on by acids. Gaseous chlorine acts violently upon them, and 

 bromine and iodine convert many of them into cymene. Many ter- 

 penes are therefore closely related to cymene, C 10 H 14 , and may be con- 

 sidered as dihydrocymene ; others, however, show a quite different 

 structure. They are oxidized quite readily with the formation of a 

 number of organic acids, and unite with gaseous hydrochloric acid to 

 form mono- or dihydrochlorides. With bromine they often form 

 characteristic tetrabromides, C 10 H 16 Br 4 . They readily yield com- 

 pounds with nitrosyl chloride, of the formula C 10 H 16 .NOC1, known 

 as nitrosochlorides, and with the oxides of nitrogen compounds of 

 the formulas C 10 H 16 .N 2 O 3 and C 10 H 16 .N 2 O 4 , known as nitrosites and 

 nitrosates respectively. The terpenes are almost all optically active, 

 and most of them exist both in dextro- and in Isevorotatory modifi- 

 cations. 



Pinene is the chief constituent in most of the volatile oils obtained 

 from the coniferse, and is also found largely in other volatile oils. 



Oil of turpentine, C 10 H 16 , is chiefly composed of pinene. It is a 

 thin, colorless liquid of a characteristic aromatic odor, and an acrid, 

 caustic taste ; it is insoluble in water, soluble in alcohol, and an excel- 

 lent solvent for resins and many other substances. When treated 

 with hydrochloric acid gas direct combination takes place and a white 

 solid substance of the composition C 10 H 16 HC1 is formed, which is 

 known as pinene hydrochloride, or artificial camphor, on account of 

 its similarity to camphor both in appearance and odor. 



Experiment 7L Through 10 or 20 c.c. of oil of turpentine pass a current of 

 hydrochloric-acid gas for some time, or until a quantity of a solid substance 



