20 SCIENCE PROGRESS 



with the formaldehyde to give C9H6N(EtI) • CHgOH, which is 

 reduced to quinaldine ethiodide. 



Synthesis of Ephedrine and "^-Ephedrine. — ^The investigation 

 of naturally occurring organic bases is being actively pursued. 

 One of the most recent syntheses is that of Spath and Gohring 

 (Monatsb., 1920, 41, 319), who have confirmed the previous views 

 of the structure of ephedrine and -v/^-ephedrine by synthesising 

 these compounds from propyl aldehyde as follows : 



CH3 • CH2 • CHO --> CH3 • CH Br • CHO "Br + ch,oh _^ 



CH3 CH Br • CH Br • OCH3 ^^^°"°^' > 



CH3 • CH Br • CH(C6H6) OCH3 ^^'^"' - > 



CH3 • CH(NH CH3) • CHCCeHg) • OCH3 i^-» 

 CH3 • CH(NH CH3) • CH(C6H5) • OH 



A 45 per cent, yield of racemic i/^-ephedrine is thus obtained 

 which was resolved by crystallisation of its ^/-tartrate. The 

 ■v/^-c^-ephedrine is identical with the natural product. By heat- 

 ing with hydrochloric acid the d- and /-"»/^-ephedrines have been 

 converted into the d- and /-ephedrines, and the latter found to 

 be identical with natural ephedrine. 



MINEBALOGY.— By Alexander Scott, M.A., D.Sc. 



Synthetic Mineralogy. — In the last account of this branch of 

 the subject in these reports (Science Progress, 15, 29, 1920), 

 mention was made of the relations between the substance 

 2CaO.Mg0.2Si02, one of the ternary compounds found in the 

 system CaO - MgO - SiOg and the natural mineral aker- 

 manite, and the facts in favour of the probable identity of the 

 two substances were indicated. With a view to the elucida- 

 tion of the problems raised by the variable composition of the 

 mineral and its probable existence as a constituent of melilite, 

 an investigation of the binary system gehlenite-akermanite has 

 been made. The former was synthesised by G. A. Rankin and 

 F. E. Wright {Amer. Jour. Sci., 39, 26, 191 5) in their work 

 on the system CaO — AlgOg — SiOg, and its optical properties 

 determined. J. B. Ferguson and A. F. Buddington {ibid., 50, 

 131, 1920) have now found that the two minerals form a con- 

 tinuous series of solid solutions with well-defined minima on 

 the liquidus and solidus curves, so that the system belongs to 

 Roozeboom's Type III. The minimum melting-point, 1,388° C, 

 is given by the mixture containing 74 per cent, akermanite 

 and 26 per cent, gehlenite. The curves showing the variation 

 of refractive indices with composition are found to be straight 



