--------------------------------------------------------------------------------
               Preparation of Hydroxylamine hydrochloride  
--------------------------------------------------------------------------------
                                          
40g KNO3 and 50g CH3COOK are dissolved in 100ml ice water. 750g finely crushed 
ice is added. Into this solution a stream of SO2 is bubbled until the solution 
smells of SO2. The temperature must be kept below 0°C through the whole reaction. 
The salt of K2[HON(SO3)2] separates and is filtered off and washed with ice water. 
The salt is dissolved in 500ml 0.5mol HCl and boiled for two hours. Still boiling 
a solution of BaCl2 is added as long as BaSO4 precipitates (maybe CaCl2 will do 
instead). The BaSO4 is filtered off and the clear filtrat is evaporated to dryness. 
The residue consists of KCl and NH2OH*HCl. Anhydrous EtOH is used for extraction 
of the Hydroxylammoniumchlorid, the KCl remains unsolved. The EtOH is evaporated 
on a water bath and the product can be recrystallised from water (mp 151°C).

Ref: Jander-Blasius, Lehrbuch der anal.u.prep. anorg. Chemie

--------------------------------------------------------------------------------