22 



COMMERCIAL TURPENTINES. 



It has been pointed out that in aging, turpentine undergoes change; 

 it becomes heavier, thicker, and deeper colored and the odor is 

 different. With age specific gravity and refractive index may become 

 higher, the quantity distilling below 170 C. less, the color deeper, 

 and polymerization with sulphuric acid more rapid, and fully as 

 complete. The increase in specific gravity or refractive index which 

 occurs with age is well shown by the results on samples Nos. 6121, 

 6127, 6135, 6137, and 6238, on which two sets of results, the higher 

 one obtained from 12 to 18 months later than the lower, are given. 

 These samples had visibly changed in consistency and color, and the 

 odor had also changed in the time elapsing between the two sets of 

 determinations. Samples which showed no visible darkening or 

 thickening had practically the same specific gravity and refractive 

 index after 18 months as at first. As has been shown, partly be- 

 cause of this tendency to change with age and also because of the 

 natural variations in the product, it is customary to specify certain 

 limits within which the results of an analysis of turpentine should fall. 

 The fixing of these limits for different grades is discussed under speci- 

 fications for turpentine. 



EXTENT OF ADULTERATION WITH MINERAL OIL. 



The data showing the extent and distribution of the adulteration 

 of turpentines, which is practically confined to the addition of mineral 

 oils, may be summarized as follows, the detailed figures being given in 

 Tables I and II, beginning on page 32. Only those samples showing 

 1 per cent or more of mineral oil are counted as adulterated in this 

 summary : 



Number and distribution of adulterated. samples. 



Buyers purchasing through factors. 



The figures indicate that only a few of the samples of producers' 

 goods are adulterated with mineral oils, while the turpentine of the 

 primary buyers and dealers in the turpentine bel^ is adulterated 

 extensively, showing 13.6 and 18 per cent of adulterated samples, 



