330 CARNEGIE INSTITUTION OF WASHINGTON. 



2. System of Qualitative Analysis including the Rare Elements. 

 An attempt has been made during the past year, with the assistance of 

 Professor W. C. Bray and Mr. E. H. Swift, to bring to a conclusion the re- 

 search on a system of qualitative analysis including all the metallic elements 

 which was carried out through a long period of years at the Massachusetts 

 Institute of Technology. Good progress has been made; and there is reason 

 to hope that dining the coming year the work may be completed and pub- 

 lished as a monograph. A new and complete, but fairly simple, procedure for 

 preparing the solution for analysis, by which practically all materials, even 

 the most difficultly decomposable, are brought into solution, has been fully 

 worked out. The method of analysis of the group of elements (comprising 

 arsenic, selenium, and germanium) which distil over upon boiling with hydro- 

 bromic acid, and of the group of elements (comprising antimony, tin, tungsten, 

 molybdenum, vanadium, titanium, tantalum, and columbium) which may 

 be left as solid oxides after treatment with concentrated nitric or perchloric 

 acid, has been brought into final form. The rest of the scheme of analysis is 

 so far advanced that the main work remaining is its preparation for publication. 



3. Determination of Structure of Crystalline Substances by X-Rays. 



The investigations on the determination of the arrangement of atoms in 

 crystals have been continued by Dr. R. M. Bozorth and Mr. A. L. Raymond, 

 with the close cooperation of Dr. R. G. Dickinson, who as National Research 

 Fellow is pursuing researches in this field in the laboratory. The work during 

 the past year has also been greatly promoted by the presence of Dr. R. W. G. 

 Wyckoff , member of the staff of the Geophysical Laboratory, who, under leave 

 of absence generously arranged for by the Director of that Laboratory, has 

 been in residence at the Institute as one of its Research Associates. 



While during previous years this field of research had seemed to be yielding 

 returns only slowly and laborously, yet, now that the methods of study have 

 been more fully developed and the types of crystals are known which lend 

 themselves to satisfactory interpretation, a wealth of interesting results is 

 being rapidly accumulated. Thus, the atomic arrangement and atomic 

 distances have been fully or in large measure determined in the following 

 complex salts: K 2 SnCl 6 , (NH 4 ) 2 SnCl 6 , K 2 Zn(CN) 4 , K 2 Cd(CN) 4 , K 2 Hg(CN) 4 , 

 K 2 PtCl 4 , K 2 PdCl 4 , and (NH^PdCL,, by Dr. Dickinson; (NH 4 ) 2 SiF 6 by Dr. 

 Bozorth; NiCl 2 .6NH 3 , NiBr 2 .6NH 3 , NiI 2 .6NH 3 , and Ni(N0 3 ) 2 .6NH 3 , by Dr. 

 Wyckoff. Silver molybdate Ag 2 Mo0 4 , hydrazine hydrochloride N 2 H 4 (HC1) 2 , 

 sodium acid acetate NaC 2 H 3 2 .HC 2 H 3 2 , and zinc bromate hexahydrate 

 Zn(Bv0 3 ) 2 .6H 2 have also been investigated by Dr. Wyckoff; phosphonium 

 iodide PHJ, by Dr. Dickinson, and cadmium iodide Cdl 2 , by Dr. Bozorth. 

 Conclusive results have been obtained by Dr. Dickinson and Mr. Raymond 

 with hexamethylene tetramine (CH 2 ) 6 N 4 , the first non-saline organic compound 

 to be successfully studied by the X-ray method. Of special interest is the 

 fact that this compound, unlike the inorganic ones thus far investigated, 

 shows a distinct segregation of its characteristic molecules. 



The experimental facilities for the execution of these researches have been 

 supplemented by securing from the General Electric Company one of their 

 newly developed, water-cooled X-ray tubes, with its auxilliary equipment, 

 the greater power of which will make possible the study of certain substances 

 that are obtainable only in the form of crystalline powders. 



