Temperature. 





Total Si. 



970° 





9-22$ 



1150 





14-89 



1250 





19-26 



1470 





41-46 



It was found 



that 



when 



saturated with 



silicon, the i 



462 Scientific Intelligence. 



Soluble. Insoluble. 



5-35$ -3-87$ 



4-02 10-87 



366 15-60 



6-63 34-83 



the metallic silver was only partly 

 silicon, the proportion of the soluble modification 

 was greater, so that when only about 2 per cent was present it 

 was practically all soluble in hydrofluoric acid. This new modi- 

 fication of silicon forms thin, yellow, transparent plates, the color 

 of which resembles the crystallized silicon made with aluminum. 

 Its specific gravity does not vary notably from that of the insol- 

 uble modification. — Berichte, xxxvii, 2540. h. l. w. 



4. Phosphorescent Zinc Sulphide.-, — It has been supposed that 

 chemically pure zinc sulphide was required for the preparation of 

 the well-known phosphorescent blende screens. In preparing such 

 screens Grune noticed, however, that the results were very vari- 

 able, and when particular care was taken to use very pure zinc 

 salts, the phosphorescence became weaker than usual. From this 

 it was evident that traces of foreign substances improved the 

 luminosity of the material, and direct experiments snowed this 

 to be the case. Copper was found to be the most satisfactory 

 impurity, and less than 1/10,000 of this sufficed to produce a mag- 

 nificent green phosphorescence. Silver, lead, bismuth, tin, ura- 

 nium, and cadmium also gave good products, while iron, nickel, 

 cobalt, and chromium gave negative results. When manganese 

 was present in the zinc sulphide a very peculiar product was 

 obtained which phosphoresced with a yellowish red light and 

 became very luminous when it was rubbed or scratched. — Berichte, 

 xxxvii, 3076. h. l. w. 



5. Atomic Weight of Rubidium. — An elaborate investigation 

 of the value of this constant has been made by E. H. Archibald 

 of McGill University, Montreal. Great care was used in purify- 

 ing the material, particularly in separating the last traces of 

 potassium and caesium, and several samples of different origin, as 

 well as of different treatment in purification, gave only closely 

 agreeing results. The ratios AgCl: RbCl, Ag: RbCl, AgBr: lib Bl- 

 and Ag: RbBr were determined with very concordant results, 

 giving a final mean value, when oxygen is taken as 16, as 85-485 

 for the atomic weight of rubidium. This result is appreciably 

 higher than the results of most of the previous investigators, the 

 value adopted in the international table being 85 4. — Jour. Chem. 

 Soc. lxxxv, 776. b. l. w. 



6. Radio-active Cinnabar. — It has been observed by Los- 

 anitsch that certain specimens of the mineral cinnabar show a 

 distinct radio-active action upon the photographic plate, but this 

 is not as strong as the action of pitchblende. It is the author's 

 opinion that the radio-active constituent of cinnabar is not identi- 

 cal with radium, and he gives to it provisionally the name radio- 

 mercury. — Berichte, xxxvii, 2904. h. l. w. 



