o72 T. HAtlA. 



(lilnto solutions of its ]\3Mlroc]iloi'ide. Dilution of 10 ces. of tlio liy- 

 droxyammonium chloride solution to 500 ces., and of another 10 

 CCS. to 1000 CCS., was made, and the solutions left all night and then 

 titrated by iodine, with the usual addition of sodium bicarbonate. 

 The 500 CCS. required then only 10.1 ces. of iodine solution instead 

 of about the 10.8 ces. which would have been wanted with that 

 dilution if the titration had been proceeded with at once, as maybe 

 seen from the first of the preceding tabular statements. The effect of 

 time upon the dilutic^n to 1000 ces. was still more marked, for this 

 required only 8.8 ces. 



Jiifhicucc of sodium chloride, sulpltate, or carbonate present m the 

 solutions : — Large excess of sodium bicarbonate gives high results, 

 but I have not made any systematic series of measurements of its 

 effects, since the use of unnecessary quantities can always be avoided. 

 But in many cases, which occur during investigations, the solution of 

 hydroxyamine to be titrated is very acid, and to neutralise this acid 

 with the bicarl:)onate is to charge the solution with sodium chloride 

 or sulphate, and enrl)onic acid. Now eitlier of these salts, when 

 present in rather large proportions, affects the titration of the hy- 

 droxyamine, while the carbonic acid is also active in this way in 

 presence of one of these salts, although by itself it appears to be with- 

 out action. Free acid should therefore be nearly all removed — hydro- 

 chloric a'.'id by evajxn'ation, sulphuric acid by addition of baryta, — 

 before the sodium bicarbonate is added. The effect of sodium 

 chloride was measured in a series of experiments which are tabulated 

 below. The solutioiis employed were : — 



Hydroxyammoniuni chloride .... ().9772 grams per liter. 



Iodine 12.G288 „ „ „ 



Sodium chloride 100.0 ,, ,, „ 



'l'he s une, charo-ed with carhoiiif ar'id. 



