1'ERoXYLAMIM sn.l'lK'N \TKS AND HYDR0XYLAMINETRI8UL] BOXATES. H 



none of the silver goes into solution, whereas a little of the reduced 

 lend peroxide dissolves and renders the salt impure. But the dissolved 

 lead is readily removed and the lead peroxide presents the advantage 



of being at hand when wanted, whilst the .silver oxide has to he 

 prepared each time and the metal afterwards recovered. Lead peroxide 

 has therefore been used in the present research. 



Fremy used either the 2/3- or the 5/6-normal potassium hydroxyl- 

 aminedisulphonate as the source of the peroxylaminesulphonate ; 

 Claus used only the latter, and Raschig chose the former. The 

 advantage lies with the 5/6-normal salt, for, when prepared from a 

 less alkaline salt, the peroxylaminesulphonate proves to be less easily 

 purified and consequently less stable. The 5/6-normal salt is always 

 so far hydrolysed in dissolving that it is converted into the 2/3- 

 normal salt, the potassium hydroxide being left in solution as noticed 

 by Claus. The presence of free alkali, however, moderates the action 

 of the oxidising agent, and to such an extent that a sufficiently 

 concentrated solution of the very soluble normal sodium hydroxyl- 

 aminedisulphonate is not attacked at all by lead peroxide. Apparent- 

 ly, therefore, lead peroxide acts as an acid oxidiser, in the form of 

 plumbic anhydride, as suggested by Fremy. 



The salt, which must be prepared just when it is wanted, is 

 produced by mixing about G grams of the 5/o'-normal hydroxy lam inedi- 

 sulphonate (or the same amount of the 2/3-normal salt together with 

 a small quantity of a potassium hydroxide) and a little more than 

 the same weight of lead peroxide (or of the silver oxide precipitated from 

 a little Jess than the same weight of silver nitrate) and making up 

 with water to 25 c.c. The mixture is agitated for 15 minutes 

 in water near to, but not above, 40°. Then, the solution is decanted 

 without delay, treated with carbon dioxide (when lead peroxide has 

 been used), and filtered, before crystallisation sets in. The solution 



