RECENT ADVANCES IN SCIENCE 389 



Frazer, Holland and Miller before the American Institute of 

 Chemical Engineers, details of which are published in the 

 Journ. Indust. and Eng. Chem. 9, 935 09i7)> is highly instruc- 

 tive. These investigators have avoided all the costly heat 

 treatments of the feldspar minerals, which have proved to be 

 economically unsound. They find that an artificial leucite 

 can be obtained by heating the finely ground feldspar with 

 strong caustic soda up to a temperature of about 275-300 C. 

 Soluble sodium silicate is a by-product of this reaction, from 

 which caustic soda can be reobtained by causticising with lime 

 and filtering off the precipitated calcium silicate. 



The artificial leucite is insoluble in water, and contains all 

 the potassium and aluminium and two-thirds of the original 

 silica of the feldspar, and yields up its constituents one at a 

 time by proper treatment with acid. The potassium is more 

 loosely held in the leucite than the aluminium, and the mineral 

 readily yields soluble potassium salts on digesting with acids, 

 which if not in excess leave all the aluminium as insoluble silicate. 

 This residue is somewhat analogous to kaolinite, but will yield 

 soluble aluminium sulphate with sulphuric acid along with 

 gelatinous silicic acid, which can be rendered insoluble by eva- 

 poration. The yield of potassium is stated to be practically 

 theoretical, and of aluminium about 86 per cent. 



The economic success of these investigations on large-scale 

 operations as a source of potassium will greatly depend on 

 the value of this aluminium recovery. 



ORGANIC CHEMISTRY. By P. Haas, D.Sc, Ph.D., St. Mary's 

 Hospital Medical School, London. 



A new and very ingenious synthesis of tropinone from com- 

 paratively simple substances is described by Robinson (/. Chem. 

 Soc. 191 7, 762). As may be seen from formula I. 



/ ! CH 5— CH, 

 CH 2 



NCH 3 CO 

 CH 2 I I 



CH i— CH 2 



\ 



1 



tropinone has a symmetrical molecule and imaginary hydro- 

 lysis at the points indicated by the dotted lines, should yield 



