68 



over, varies. The latter is best obtained by adding 52 grammes of 

 cineol to an etheric suspension of' 56 grammes of CHgM^I, obtained 

 from 8 grammes of Mg and 48 grammes of CH3I ; the whole mass 

 is heated for a few hours and left for 3 or four days. 



Then the ether is distilled off, in which but very little cineol 

 goes over, the residue is heated up to ± 160° on a sand bath, a 

 very wide exit tube is placed on the flask and the reaction proceeds 

 without further supply of heat. Thus from 30 — iO grammes of distillate 

 are obtained and from 4 — 5 L. of gas. There is, however, always 

 some liquid left behind in the flask ; it is obtained by treating the 

 residue farther in the usual way ; the thus obtained liquid is the 

 same as that which distills over. The latter is first washed with a 

 thiosulphate solution and then fractionated in vacuo, collecting every- 

 thing together that goes over at 21 mm. to 85°. Then the distillation 

 is stopped, because then the residue begins to decompose with split- 

 ting off of iodine. What is distilled over is shaken a few times 

 with a 507o resoreine-solution for the removal of unchanged cineol, 

 which is present in a fairly large quantity ; then it is dried on 

 chloric calcium and finally distilled over metallic sodium. Then a 

 liquid is obtained of b.pt. 170° — 178° at 759 mm., consisting of a 

 mixture of hydrocarbons C,oHjg. The elementary analysis namely 

 gave: (burned with lead chromate in a closed tube): C = 87, 847o; 

 H = 12.007„ (calculated for C^.H,^ : C = 88.157„ ; H — 11.857J, 

 the determination of the physical constants of the fractions obtained 

 by repeated fractionation : 



fraction b.pt. 170°— 172°, 5; Sp. Gr-ieo = 0.841 



nzjiGo = 1.4679 



fraction b.pt. 172° 5—175' 



fraction b.pt. 175°— 178°: 



Mol. Refr. = 44.99 

 Sp. Gr.16 = 0.846 

 nz)i6o = 1.4706 



Mol.Refr. = 44.94 

 Sp. Gr.160 = 0.853 

 n^jieo = 1.4752 

 Mol.Refr. = 44.95 

 Mol.Refr. = 45.25. 



Calculated for 0^ Hjg 2 f 



Besides, the fact that in not a single way a crystalline product 



could be obtained from any of these fractions points to the presence 



of a mixture. I tried the preparation of the tetrabromide according 



to Wallach ^) in alcohol ether, in sulphuret of carbon, and in 



1) Wallach, Annalen 227, 280 (1885). 



