RECENT ADVANCES IN SCIENCE 379 



that of the interior of Western Australia, is a criterion of 

 elevation of the land ; and difference of laterite levels suggests 

 faulting. The actual deposition of laterite is believed to be 

 effected by the leaching of subsoil salts by rainfall, followed by 

 capillary action during the ensuing drought, with the result 

 that the solution is drawn to the surface and the dissolved 

 matter deposited as concretions within the soil. 



The origin of ore deposits by laterisation is discussed by 

 W. G. Miller (Rept. Ont. Bur. Mines, 191 7, 26, pt. 1, 318-34). He 

 shows that iron (Cuba), nickel and cobalt (New Caledonia), 

 especially, are concentrated by this means ; and also that 

 manganese, aluminium in the form of bauxite, and gold, may 

 be formed as lateritic ores. The nickel ores of New Caledonia, 

 although unquestionably of lateritic origin, do not conform to 

 the accepted definition of laterite, inasmuch as they contain more 

 than five per cent, of combined silica. Similarly it is shown that 

 the term laterite can only be properly applied, on this criterion, 

 to the upper layers of the Cuban iron ores, as the combined 

 silica increases considerably with depth. 



Davis, W. M., Metalliferous Laterite in New Caledonia, 

 Proc. Nat. Acad. Set., U.S.A. 191 8, 4, 275-80. (Discusses the 

 relation of the laterite to the physiographic development of the 

 island.) 



Before his unfortunate death from wounds the late 

 Lt. R. C. Burton had completed a paper on the origin of the 

 laterite of Seoni, Central Provinces, India, which is now pub- 

 lished by the Geological Survey of India (Rec. G. S. India, 191 7, 

 48, pt. 4, 204-18). This laterite is of the high-level type, and 

 occurs at elevations between 1,900 and 2,100 feet above sea 

 level. It is of the usual ferruginous cellular type, and directly 

 overlies the Deccan Trap. It is believed to be partly of chemical 

 origin and partly a detrital lake deposit. 



CRYSTALLOGRAPHY. By Alexander Scott, M.A., D,Sc. 



Crystal Structure.— Since this subject was last treated in these 

 reports (July 191 7) the structure of a number of crystals has 

 been investigated by means of X-ray analysis, many of the 

 results being obtained by a modified method which greatly 

 extends the applicability of this type of investigation. This 

 modification, which is due to P. Debye and P. Scherrer (Nachr. 



