HYDKOXYLAMINE AND ITS SALTS. — ROSS. 107 



tion only after adding 12cc. of^Xao H P O4. A larger volume of 

 sodium phosphate added gave results too high thus : — 



Vol. of (N Hg H), S . Vol. of Na._, H P 0.j Vol. of iodine 



taken. added. r...r re(iuiied. 



occ. 12cc. 10.04ec. 



5 " 24 " 10.96 " 



5" 36" 11.42" 



5" 48" 11.63" 



5" 60" 11.78" 



When titrating, iodine was added until it gave with the 

 solution a blue color lasting for a moment. The same amount 

 of starch solution was taken for each titration — -being measured 

 from a burette. It was found that by adding unequal amounts 

 of starch irregular results were obtained. This was due to the 

 fact that by using a large amount of starch the blue coloration 

 was found to fade out less quickly than with a less amount, 

 making it almost impossible to identify the true end point in 

 both cases, 



Haga,^ in his experiments on the volumetric estimation of 

 hydro xylamine by iodine, used sodium acid carbonate for pro- 

 ducing a non-acid solution. He showed that to get best results 

 by this method, solutions (1) should not be excessively dilute ; 

 (2) should contain very little alkali salt ; (3) should not have 

 more carbonate added during titration than is necessary to take 

 up the hydriodic acid formed. 



To find the effect of varying the dilution of the hydroxy- 

 lamine salt when in presence of sodium phosphate, I made a 

 series of determinations varying the volume of the solution 

 titrated from 25 cc. to 250 cc. As far as I was able to deter- 

 mine, this range of dilution did not produce any effect on the 

 titration. 



A series of titrations was also made with sodium sulphate 

 present in solution. Although amounts of this salt were added 



' Journ. Chem. Soc. (London), 51, 791 (1887). 



