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 XLIII. Intelligence and Miscellaneous Articles. 



ON THE COLORATION OF PEROXIDE OF NITROGEN. 

 BY M. SALET. 



T™!E ° f Per °f ide °V ,it J r °S en (hyponitric acid) has several 

 *» ; emarkab!e L Properties. Its density rapidly decreases up to 43° ■ 

 the decrease then becomes slower, and it ceases at 150°* It fe 



d epe'nrfror 6 n bSe -?1 *"" ^ C ° lcUr ° f '"vapour gradually 

 deep red'. ? eIlomsb brown * becomes reddish brown and the,, 



peculfarfties! *** ^^ *" ""** ^ C ° DnQt eX P lain these *™ 



Wurtz supposes that the molecule of peroxide of nitrosen at a low 



temperature contains N*0*= 2 vols., and that on be n^heate it Z 



fotme s 5 , c] SS0Ci t ed / nt ° 2 m ° leCUleS - N ° 2 ' each occupy ngVo 

 volumes (ChimieModerne, p. 156). This decomposition which is 

 he inverse of polymerization, is not without examples in chemitrv 

 the cases of cyamc acid, styrolene, &c. may be adduced ' C " em ' Stry ' 

 Supposing that NO 2 and N*0* expand regularly, it is eas V to cal 

 culate the composition of a mixture of these two bodies which for a 

 nZger PeratU1 " e W0UM " aVe tHe denSit ^ f ° Und for P-oxide° r „t- 



the^ohV™ 'f 15 denS ') y r / fCTred t0 hydr °S en < that *■ t^ weight of 

 the volume of peroxide of n.trogen equal to that of H) ; let /and b 



lume T I 8 '" T^ 0f N ° 2 and N2 °* contain ed in this vo- 

 ume As we have i(N0 2 =23 and |(N 2 Cf)=46 for the theore 

 icaldens.faesof NO* and W 0< referred to hydrogen, the fol owTne 



relations may be established : mowing 



23 ^46 ' 



whence 



«=D-46, 6=2D-46. 

 Table A gives the values of « ; that is, the proportion in weight 



of NO 2 calculated from the experimental densities determined with 

 so much accuracy by MM. St.-Claire Deville and Troostf . It w 11 

 be observed that these latter numbers are a little too high corre 

 sponding to an experimental density a little weaker than the theo- 



This being granted we may reason as follows .—Since peroxide 

 of nitrogen is colourless at a temperature at which its density pro- 

 bably corresponds to N^O*, and its colour is deeper the nearer 

 we approach the temperature at which the molecular condensation 

 corresponds to the formula NO*, let us assume that N* O* is colon " 

 iothes^s ' "^ inVeSti ^ ate the consequences of this hy. 



* MM. H. St.-Claire Deville and Troost. 

 t tomptes Rendus, vol. lxiv. p. 237, 



