174 REPORT OF NATIONAL MUSEUM, 1890. 



The object of this arrangement is to indicate gaps in the series of 

 known elements which are likely to be filled in future by the discovery 

 of new elements, the properties of which may be foretold with more or 

 less certainty from their position in the series. 



The existence of the three metals, scandium, gallium, and germanium, 

 was thus predicted before they were discovered. 



The position of some of the elements in the table is not yet well estab- 

 lished. The metals in the last row are provisionally placed in groups 

 by themselves. 



The specimens here brought together under the head of chemical 

 collections are catalogued in different registers. The last entries under 

 the respective heads are — 



Chemicals. 



June, 1889 78067 



June, 1890 78082 



Paints and Dyes. 



June,1869 9041 



June, 1890 9041 



Oils, Gums, Resins, etc. 



June,1889 2713 



June, 1890 2740 



A specimen label will indicate the general character of all. Such 

 labels are usually attached to bottles, and as these are never large, it is 

 necessary to condense the text of the labels as much as possible. 



GERMANIUM, Ge. — Valency 4; atomic weight 72; specific 

 gravity 5.469 at 2o°.4 C. 



A grayish-white, lustrous, crystalline, brittle metal, easily pul- 

 verized, discovered by C. Winkler in 1886, in argyrodite, a 

 mineral found near Freiberg, of which it constitutes about 

 7 per cent. Unchanged in air, soluble in aqua regia. Fuses 

 readily. 78,072. 



Gift of Dr. C. Winkler through Prof. F. W. Clarke. 



Specimen prepared by C. Winkler. 



The existence of this element was predicted from the atomic rela- 

 tions of the elements as shown by Mendelejeff's table. 



A system of classification for organic and inorganic compounds will 

 soon be necessary, and will be prepared as soon as time and opportunity 

 may permit. 



A preliminary plan for an exhibit at the World's Columbian Exposi- 

 tion at Chicago, illustrating chemistry and the chemical industries, has 

 been prepared. 



All the collections are now in excellent order. A large and valuable 

 industrial exhibit could be very quickly made if floor-space and cases 

 could be provided. Many of the specimens are already mounted and 

 stored in drawers, ready to be placed in cases and labeled. 



