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 LVI1I. Intelligence and Miscellaneous Articles. 



ON THE PHOSPHORESCENCE OF RAREFIED GASES. 

 BY M. MORREN. 



1. "DURE and dry oxygen, however rarefied, is never phospho- 

 -*- rescent when traversed by the induction spark. 



2. Any other gas, simple or compound, if rarefied when alone, 

 never presents the phenomenon of phosphorescence. 



3. A mixture of oxygen and nitrogen in the proportion of 37 per 

 cent, of oxygen gives a phosphorescence, but it is feeble and very 

 little durable. 



4. It becomes more pronounced if to the preceding gaseous mix- 

 ture a little vapour of monohydrated nitric acid is added. 



5. The phosphorescence is splendid and permanent if to the above 

 gaseous mixture a drop of Nordhausen sulphuric acid or a small 

 quantity of anhydrous sulphuric acid is added. 



6. The same result is attained by passing the induction spark 

 through a rarefied mixture of the three gases, oxygen, nitrogen, and 

 sulphurous acid, in the following proportions : — 



Oxygen 200 



Nitrogen 100 



Sulphurous acid 150 



7. In all cases the phosphorescence is produced by the successive 

 decomposition and recomposition of a singular body well known to 

 chemists, the crystallized body produced in the manufacture of 

 sulphuric acid, and which has the formula NO 3 2 SO 3 . When in 

 the state of vapour and very rarefied, the spark traversing it sepa- 

 rates it into two parts, NO 3 and 2 SO 3 , which have only feeble affi- 

 nities for each other. When the electricity ceases to pass, the 

 elements NO 3 and 2 SO 3 cannot coexist in the vaporous state with- 

 out recombining, especially in the presence of oxygen. During these 

 molecular evolutions, and while the two parts of the compound are 

 separated, the phosphorescence is kept up. Everything leads to the 

 belief that it is anhydrous sulphuric acid, which, in its passage from 

 the state of vapour to the solid state, is the seat of this luminous 

 phenomenon. 



8. Sulphuric acid is not the only acid which can produce this phe- 

 nomenon. Nitric and probably other acids present it also. And it 

 appears probable that there is a compound, analogous to the pre- 

 ceding, in which SO 3 is replaced by NO 5 . 



9. The compound NO 3 2 SO 3 can be made directly, under the'in- 

 fluence of the apparatus described in the research of which this is 

 an abstract. 



10. In order to obtain Geissler's tube very strongly luminous and 

 for a long time, nitrogen, and not carbonic acid, must be taken ; for 

 the latter, though luminous, has the inconvenience of easily decom- 

 posing. Quicksilver vapour must be mixed with it, by rarefying the 

 air by the barometric vacuum, and not by the air-pump. 



1 1 . The spectra of the gases in this case, abstracting from the well- 

 known lines of mercury, may be studied in day-light with great ease and 

 accuracy. To obtain a spectrum accurate in every respect, the prism 



