106 CONTRIBUTION TO THE STUDY OF 



Any decomposition is readily detected by the odour of am- 

 monia given oti', or by adding to a small portion in solution a 

 few drops of a neutral solution of phenol-phthalein. A solution 

 of hydroxylamine in water appears to be stable at ordinary 

 temperatures. A portion of a solution kept for several weeks in. 

 a warm room gav^e no trace of a coloration when treated with 

 a few drops of a perfectly neutral solution of phenol-phthalein- 



Titration of Hydroxylamine hy Iodine. 



The only fairly trustworthy method for tlie volumetric esti- 

 mation of hydroxylamine is that devised by Haga' and modified' 

 by Adamsl This volumetric estimation is performed by add- 

 ing an ^ solution of iodine in potassium iodide to hydroxylamine 

 solution in presence of di-sodium phosphate, as long as the former 

 is bleached — using starch as indicator. Although this method 

 gives better results than any of the others which have been 

 suggested, yet it was found to be far from satisfactory. The 

 end point is very hard to determine, as the blue color given with 

 the starch fades out immediately^ It was further noticed' 

 that the results obtained were influenced considerably by the- 

 amount of .sodium pho.sphate in solution. 



In the following experiments the solutions used were : — 

 solution of hydroxylamine sulphate containing 8.2104 gms. per 

 liter (^^) ; of iodine, containing 12.685 gms. per litre (~) : and 

 of di-sodium phosphate, containing 59.7172 gms. per litre (^). 

 The solution of iodine was standardised by copper. 



According to the equation : 

 (N Hs O H)2 S O4 + 2 lo = 4 H I + Ho S O4 + No O + H^ O, 

 5cc. of j"^ hydroxylamine sulphate solution = lOcc. of ^ iodine 

 solution. When making the titration it was found that 5cc. of 

 j^ hydroxylamine .sulphate would bleach lOcc. of f-^ iodine solu- 



» Journ. Chem. Soc. (London). 51.794 (1887). 

 2 American Chem. Journ., 28,198 (1902). 



