328 CONTRIBUTION TO STUDY OF HYDROXYLAMINE. — MACKAY. 



Preparation of Solutiovs. 



The best method for the analysis of hydroxylamine, aceord- 

 ino- to the investitJ^ations of Maxwell Adams/ is the titi-ation 

 by iodine in the presence of tertiary sodium phosphate. He, 

 however, states that it is not very trustworthy. 



My experience has been the same. Working with a standard 

 solution, concordant results could be obtained by always using 

 the same amount of phosphate, but where an unknown amount 

 of hydroxylamine was present in the solution, there being no 

 guide as to the amount of phosphate to be added, very un.satis- 

 factory results were obtaired. The end point is also very 

 uncertain, the blue color of the starch fading out almost imme- 

 diately. 



Accordingly in making up my standard solutions, I pro- 

 ceeded directly from the weight of the crystalline hydroxy- 

 lamine itself, which should give more accurate results than 

 standardization by the iodine titration. 



As the solutions when once used in the conductivity cell 

 could not be used again on account of decomposition, each con- 

 centration required was made up separately. In the case of 

 2, 5, and 10 normal solutions, 50cc. and 25cc. graduated flasks 

 were used, and as all of this was needed to rinse the cell and to 

 fill it, a comparatively large amount of hydroxylamine was used. 



The flasks used in making up the solutions %vere 500cc., 

 400cc., 250cc., ISOcc, lOOcc, 50cc., and 25cc. 50cc. and 25cc. 

 pipettes, a 1 Jcc. pipette graduated to 1/lOcc, and a 50cc. burette 

 were used for diluting. All were carefully calibrated at 18° C. 



The various concentrations were made up in the usual way, 

 by dissolving a weighed quantity of hydroxylamine in so much 

 water, removing a portion in a pipette, adding required amount 

 of pure water to bring to the reyuired standard, and then fllling 

 up to the mark with the solution which had been removed in 

 the pipette. 



1. Loc. cit. 



