— 82 — 



oil the greater part only distilled over above that temperature. 750 g. oil, 



being fractionated three times, gave: — 



from 40 to 150° 53 g. or about 7°/o, 

 „ 150 „ 160° 200 g. „ „ 30°/o, 

 „ 160 „ 174° 160g. „ „ 20°/o, 

 „ 174 „ 178° 290 g. „ „ 40°/o. 



The above figures by themselves are sufficient indication that, in 

 contradistinction to the ordinary oil, the abnormal distillate was not a 

 uniform body. The fact that the thio-urea obtained from it, which soli- 

 dified very slowly, had no clearly defined melting point (67 to 70°) pointed 

 to a mixture of several substances. 



Dimethyl sulphide, CH 3 S-CH 3 . The first drops of the initial 

 fraction (b. p. 40 to 119°) contained small proportions of a highly volatile 

 sulphurous substance of a disagreeable-sweetish odour, which must be 

 regarded as dimethyl sulphide from the fact that it gave precipitates with 

 solutions of mercuric chloride and of platinum chloride, as well as 

 because of its very low boiling-point. This compound was first discovered 

 by Power and Kleber 1 ) in peppermint oil, and ^afterwards by us also in 

 Reunion and African geranium oil 2 ). 



Allyl cyanide, CH 3 • CH : CH • CN. The analytical values of a fraction 

 amounting to a few grams, which passed over between 120 and 123°, 

 and which also, it should be added, contained sulphur, (di 5 o 0,8570; 

 sap. no. 47,7) pointed to the probable presence of allyl cyanide. 



This suspicion was confirmed by the formation of an acid boiling 

 at about 184°, with an odour reminding of the fatty acids. This acid 

 was generated during the process of saponification with alcoholic potash. 

 It was oily, but when left to stand in the cold for several days it soli- 

 dified in crystals; m. p. 70°. Unfortunately the quantity available was 

 too small for repeated purification and for the positive identification of 

 the substance as crotonic acid, of which the m. p. is 72°. 



Those portions of the intermediate fraction distilling over between 

 130 and 150° of which the b. p. fell between 137 and 139°, and which 

 might be expected to contain isopvopyl mustard oil were tested for that 

 body. But the analysis of the oil itself as well as of the corresponding 

 thio-urea (m. p. 64 to 69°), showed that notwithstanding the low b. p. we 

 had to deal for the larger part with the ordinary allyl compound, with 

 traces, however, of some impurity to which the badly-defined m. p. of the 

 thio-urea was due. Similarly, the portions of oil boiling between 158 and 

 170°, or their thio-ureas, proved upon analysis to be only mixtures of the 

 corresponding allyl and crotonyl compounds of the higher fractions of the 

 mustard oil. None of the attempts that were made to detect in them 



*) Report October 1896, 58. 

 2 ) Report April 1909, 55. 



