108 



i 



to turpentine oil. According to H. Wolff 1 ) such additions are scarcely 

 capable of detection. On the one hand, when it is being distilled with 

 turpentine oil, the greater part of the last runnings passes over at a lower 

 temperature than when fractionated by itself; on the other, when the 

 mixture is treated with concentrated or fuming sulphuric acid much more 

 material is separated out from it than was to be expected from the 

 quantity of the residue. It would appear that in the presence of high- 

 boiling turpentine oil constituents the action of the sulphuric acid loses 

 in intensity. In the case of pure turpentine oils also, as soon as Testi- 

 fication has perceptibly advanced, treatment with sulphuric acid results 

 in increased separation. When the evaporation-residue has but slightly 

 increased, and the separation with fuming sulphuric acid shows a marked 

 increase, the addition of waste -products to the turpentine oil under 

 examination may be suspected. Where the resinification is considerable, 

 there is no means of distinguishing at all. 



With the object of testing turpentine oil for the presence of petro- 

 leum distillates or colophony, R. Marcille 2 ) ascertains the quantity of 

 90 p. c. acetic acid which is required to dissolve a given quantity of tur- 

 pentine oil. As the degree of solubility of turpentine oil and its adulte- 

 rants differs, the presence of additions may thus be ascertained. Another 

 method adopted by Marcille is to mix turpentine oil with sulphuric acid 

 in an apparatus devised by Tortelli, and to determine the increase of 

 temperature which results as an indication of the presence of adulterants. 



Some time ago we referred to the apparatus for the estimation of 

 benzines in oil of turpentine by means of fuming nitric acid which has 

 been described by Marcusson and Winterf eld 3 ). Marcusson 4 ) has now 

 proposed a modification of the method, by which 10 cc. of the oil under 

 examination is introduced in the course of about half an hour into 30 cc. 

 fuming nitric acid (d 1,52), the acid having been previously brought to a 

 temperature of —10° in the glass apparatus devised by Marcusson and 

 Winterfeld. After about 15 min. from 75 to 80 cc. cooled concentrated 

 (not fuming) nitric acid (d 1,4) is added. If no oily separation now becomes 

 perceptible upon the acid, the oil is free from benzine. The paper further 

 describes methods for testing for benzene hydrocarbons and for thefl[ 

 simultaneous estimation of benzine and benzene hydrocarbons, for the 

 particulars of which we refer to the original. 



As the outcome of his investigations, Marcusson has found that the 

 nitric acid method is suitable for the estimation of benzine and of benzene 



2 ) Farbenztg. 17 (1912), 1492. Quoted from Chem. Zentralbl. 1912, I. 1930. 



2 ) Bull. Soc. chim. IV. 11 (1912), 762. 



3 ) Chem. Ztg. 33 (1909), 987; Report April 1910, 114. 

 *) Chem. Ztg. 36 (1912), 413, 421. 



