1^2 On the Decompojttion of Azotic 



8. This phenomenon is almoft conftant during the long 

 winter in the polar regions, and is the more uncommon the 

 nearer the equator. 



9. Southern lights have been obferved alfo in the regions 

 near the fouth pole. 



10. The northern lights are often accorapanied with light- 

 ning, and a noife like that of eletSlricity; while the lightning 

 proceeds partly from the middle of the northern lights, and 

 partly from the neighbouring clouds. 



•VII. 



The Lunar Period of Ntfietcen Years. 



It appears that the general temperature of a year returns 

 every nineteen years ; an epoch when the phafes and pofi- 

 tions of the moon in regard to the earth are again the fame. 



I might add more refults, but I (hall coftfine myfelf to 

 Ihofe found moft conftant by obfervation, and conclude with 

 wiHiing, that the zeal of obfervers may contribute to confirm 

 more and more the certainty of thefe Axioms, or to difcover 

 new ones. 



IX. On the Decovipqfition of Azotic into Hydrogen and 

 Oxygen Gas, by M. Girtanner, and on the radical 

 of the Muriatic Acid. A Letter from Van Mons, of 

 lirufjels, to Delamthcrie* . 



I 



TAKE the earliefl: opportunity of informing yon, that 

 Girtanner has dccompofed azot, and reduced it to hydrogen 

 and oxygen, in the proportion of 0*93 of the former and 

 0-07 of the latter. From this it feems to follow, that azot, 

 ammonia, water, atmofphcric air, Sec. are compounds of 

 thefe two principles in varied proportions. In analyfing air 

 we do not feparate but compound the azotic gas by fub- 

 trafting a part of oxygen from the hydro-oxvp;en fluid, which 

 conftitutes that air. This is, perhaps, the reafon why coni- 

 buftion is more lively in pure oxygen gas, or orvgcn gas not 



* From Journal de Phjique, an. 8. 



engaged 



