Vol. X, No. 8.] Action of Nitric Oxide on Metallic Peroxides. 289 

 [N.8.] 



of nitric oxide on a mixture of lead peroxide and water both 

 lead nitrite and lead nitrate are formed. 



4. This fact was further confirmed quantitatively. Twen- 

 ty-five cubic centimetres of the yellow solution obtained by 

 passing nitric oxide through water containing lead peroxide 

 were precipitated with sodium sulphate, and after filtering off 

 the lead sulphate the clear liquid was diluted to 100 cc. in a 

 measuring flask. Five cubic centimetres of this solution 

 shaken with concentrated sulphuric acid over mercury in a 

 Crum mitrometer gave 3-30 cc. of nitric oxide measured over 

 water at 30*5 G and 756*2 mm. pressure (tension of aqueous 

 vapour at 3050 C = 32*463 mm.). Ten cubic centimetres of 

 the solution similarly treated gave 6-8 cc. "of nitric oxide. 

 The total weight of nitrogen present, therefore, in 10 cc. of the 

 diluted liquid = -0036 gram. 



5. For the estimation of the weight of nitritic nitrogen 

 present, the Rupp method was employed. Twenty-five cubic 

 centimetres of N/10 potassium permanganate solution were 

 added to 10 cc. of the diluted liquid and a few crystals of sodium 

 carbonate dissolved in the mixture. The solution was warmed 

 on the water bath for fifteen minutes, cooled, acidified with 

 dilute sulphuric acid, and excess of potassium iodide then 

 added ; the liberated iodine was titrated with N/10 sodium 

 thio-sulphate (reduction factor 101) of which 20*6 cc. were 

 required. As the deci-normal solution of potassium perman- 

 anate employed had been lying unused for some time it was 

 decided to redetermine its strength by titration. Twenty- 

 five cubic centimetres of the liquid were found to be exactly 

 equivalent to 24-6 cc. of N/10 sodium thio-sulphate (reduc- 

 tion factor 1-01). The volume of potassium permanganate 

 solution, therefore, used up in oxidizing the nitrite = 101 

 (24-6-20-6) cc. or 4'04 cc. 1 cc. of N/10 KMn 4 = 00345 

 Na N0 2 . Consequently the weight of nitritic nitrogen present 



•0028 gram. It will be seen that this is less than -0036 

 gram., the total weight of nitrogen contained in 10 cc. of the 



6. We 



0008 



lead nitrate are formed by the action of nitric oxide on a 

 mixture of lead peroxide and water. The former is evidently 



obtained according to the eauation : 



PbO £ + 2NO==Pb(N0 2 ) 2 



The formation of lead nitrate is not so easily understood. If 

 the passage of the gas through the mixture is prolonged and 

 the whole of the lead compound allowed to take part in the 

 reaction a yellow powder insoluble in water is left behind. 

 This dissolves in dilute acids without evolution of nitrous 

 fumes and the clear solution gives a white precipitate with 



