47S Scientific Intelligence, 



tures were analyzed. It was found that the combustion of a 

 flame can be maintained in the presence of varying quantities of 

 carbon dioxide, up to as much as 75 per cent, so long as there 

 remains a definite proportion of unburned oxygen in the mixture. 

 For the same combustion the minimum proportion of unburned 

 oxygen at which extinction occurs varies within narrow limits. 

 For example, extinction took place in the following mixtures : 



COo 



2 



No 



Per cent 



Per cent. 



Per cent. 



with the candle flame : 







3'6 



16-0 



80-2 



10-8 



17-0 



72*2 



27-8 



195 



52-7 



500 



21-2 



27'9 



78- 



22* 





with the alcohol flame : 







6-7 



14-3 



79-0 



20*3 



13-0 



66-7 



with the gas flame : 







10-4 



11*0 



78-6 



13-3 



11-3 



75-7 



34-4 



11-2 



54-4 



The interesting result is reached, therefore, that, contrary to 

 the prevailing view, carbon dioxide has but little greater effect 

 upon flames than the same amount of nitrogen, but it should be 

 mentioned that in the investigation under consideration it was 

 noticed that when combustion is taking place in the presence of 

 a certain proportion of carbon dioxide, the hydrogen of the sub- 

 stance burns alone, forming water, while the flame smokes, and. 

 the carbon dioxide increases but little or not at all. — Bull. Soc. 

 Chem., xxix, No. 5. h. l. w. 



4. The Non-conductivity of Metallic Hydrides. — Moissan 

 has found that the hydrides of potassium, sodium, rubidium and 

 caesium in compact layers 5 cm long do not conduct the electric 

 current, and that the fused hydrides of calcium and lithium 

 behave in the same way. From these results the author con- 

 cludes that hydrogen is not analogous to the metals, but corre- 

 sponds to the non-metals, in these compounds, and that these 

 hydrides cannot be considered as alloys of hydrogen with the 

 metals. — Comptes Rendus, cxxxvi, 591. h. l. w. 



5. Heat Spontaneously Evolved by Radium Salts. — It has 

 been shown by Curie and Labokde that the salts of radium 

 evolve heat continuously. When one junction of a thermo-elec- 

 tric couple was surrounded by radiferous barium chloride con- 

 taining about one-sixth of pure radium chloride, and the other 

 junction was similarly enclosed in pure barium chloride, a differ- 

 ence in temperature- was indicated, which amounted to 1*5°. 

 The amount of heat evolved in a given time was determined 

 quantitatively by comparison with a wire of known resistance. 



