io 7„ - , 



15% » • 



20 7o .. . 



25% » i 



30 7 .- . 



35 7 .. . 



40 7o - . 



45°/. » - 



- 78 - 



0,81 -j- 1 cc. = 1,81 cc, and 10 cc. of an oil containing 3O°/ benzene, 

 3,63 cc. This surplus however only applies to oils containing not more 

 than 20% benzene; oils with more than 5O°/ benzene even show a con- 

 siderable deficiency. The author has drawn up the following figures: — 

 When about 1,25 cc. are separated off, about 5 °/ by vol. adulteration 

 ?? *»/** »» " " »» 



» 2,00 „ „ „ „ 



11 2,50 ,, ,, ,, ,, 



,, 2,80 „ „ „ „ 



'» 3^35 j» " v >> 



»» 3>75 " " " " 



»> 4'^5 »> >j »> >> 



» 4,5° » » >> » 



For the quantitative estimation of benzene in turpentine oils, etc. 

 B 6 h m e prefers S c h r e i b e r and Zetzsche's 1 ) method, according to which 

 for a mixture of equal parts by volume of turpentine oil and pure 

 benzene, the bromine number 1,115 (g. Br per 1 cc. turpentine oil) 

 was found. The bromine numbers of pure turpentine oils are on the 

 average 2,20; only very old turpentine oil whose bromine number 

 lies below 2,0, will give incorrect results. 



With regard to these statements by Bohme, H. Herzfeld 2 ) re- 

 marks that he can confirm the errors of the method in the case of 

 a large admixture of benzene, but that, even when small quantities 

 are added, he obtains unsatisfactory results. In the last-named cases 

 he fractionates the substance and examines the individual fractions. 

 The residue remaining behind in the treatment with sulphuric acid is 

 further examined by Herzfeld in doubtful cases, after refracto -metric 

 examination with fuming nitric acid, especially in the presence of resin oils. 



In his studies on the use of dimethyl sulphate for the detection 

 and the estimation of tar oils in mixtures with resin oil and mineral oil, 

 E. Valenta 3 ) has also observed the behaviour of dimethyl sulphate 

 towards fatty oils, turpentine oil, and pinolin. Pinolin and tur- 

 pentine oil, when shaken with equal parts of dimethyl sulphate, cause 

 an increase in the volume of the layer of dimethyl sulphate, as about 

 30 /o °f tne above-named substances are dissolved. Pinolin imparts 

 an orange colour to the mixture; pure turpentine oil does not colour 

 it, but a mixture of turpentine oil and dimethyl sulphate causes a large 

 increase in the temperature, whilst pinolin with dimethyl sulphate 

 produces only a scarcely perceptible rise in the temperature. The 

 author believes that these reactions can be employed with advantage 

 in the testing of turpentine oil for an admixture of pinolin. 



*) Chem.-Zeitg. 23 (1899), 676. 



2 ) Chem.-Zeitg. 30 (1906), 697. 



3 ) Ibidem 266, 



