56o SCIENCE PROGRESS 



connection with certain problems relating to the felspars, 

 especially with reference to the relations of orthoclase and 

 albite to perthite. Although the equilibrium relationships of 

 the former minerals are not completely known, thermal analysis 

 has indicated the possibility of the breakdown of a solid solu- 

 tion at some temperature below the solidus curve, and it is 

 believed that perthite is the resultant product. In order to 

 test this view, S. Kozu and Y. Endo (Set. Rep. Tohoku Univ., 

 (3), 1, I, 1 921) have made X-ray analyses of adularia and 

 moonstone, both in the condition as found in nature and after 

 heat treatment to various temperatures and quenching. The 

 structure of natural adularia indicates a simple solid solution 

 in which corresponding atoms replace each other without inter- 

 ference with the structure (cf. L. Vegard and H. Schjelderup, 

 Zeit. phys. Cheni., 18, 93, 191 7). In moonstone, however, 

 the Laue pattern shows a duplication of many of the spots, 

 indicating inhomogeneity of the structure, there being present 

 two types of spacing with monoclinic symmetry. The heated 

 samples of adularia show practically the same structure as the 

 untreated up to the highest temperature tried, 1,060° C. In 

 the heated samples of moonstone, the spots in the " doublets " 

 tend to approach each other as the temperature of heating 

 rises. Treatment to a temperature just above 1,060° C. results 

 in the coalescence of the constituent spots of the doublets, indi- 

 cating that only one type of solution is present. At about 

 1,190° C. the crystalline structure disappears, as the result of 

 the material melting. 



From a similar examination of schiller spar, the authors 

 conclude that schillerisation is due to the interference of light 

 waves passing through the two types of lattice. In another 

 paper [Sci. Rep. TShokii Univ., (3), 1, 19, 1921) S. Kozu and 

 M. Sizuki give chemical and optical details for the Korean 

 schillerised felspar, while the composition and fusion pheno- 

 mena of sanidine from the Eifel are discussed by S. Kozu and 

 K. Seto (ibid., (3), 1, 25, 1921). 



By means of X-ray examination E. W. Washburn and 

 L. Navius {Journ. Amer. Cer. Soc, 5, 565, 1922) have examined 

 the products of calcination of chalcedony and flint. The 

 nature of both of these minerals has been in some doubt, 

 although Fenner suggested that the former was composed 

 essentially of quartz. This is now verified by the X-ray 

 examination, and it is shown that both minerals are mainly 

 composed of a very finely divided form of quartz. The effect of 

 calcination is likewise shown to be transformation into cristo- 

 balite. Attention might also be called to the use of similar 

 methods in connection with the investigation of such metallic 

 oxides as those of iron, aluminium, cobalt, nickel, etc., when 



