IMIDOSULPHONATES. 9I 



dilute nitric acid, insoluble in water. Its partial dissolution in nitric 

 acid leads to the formation of the hemi-hydroxy-lead imidosulphonate. 

 It has scarcely any action on moist red litmus with which it is left in 

 contact. It is insoluble in solutions of its mother-salts, and unaffected 

 in composition by them. 



Heated even at 130° it loses no water. When sufficiently hot it 

 gives off, first water, then ammonia, then again water, and then it 

 blackens through formation of sulphide, and then it evolves sulphur 

 dioxide. The loss of water and ammonia is explained by the 

 equation : — 



8(HO).5Pb,N(S03)2 = 6PbO + aPbSOg + -SPbSOi + NH3 + N2 + 60H 

 Then the les'.d sulphite becomes, as usual by the rising temperature, 

 partly lead sulphide and sulphate, partly lead oxide and sulphur 

 dioxide. At a fusing heat the sulphide and oxide would of course 

 react. 



Two preparations were analysed, a and h : — 



Calculation. Pound. 



( H0Pb)3N (803)2, PbCiHsO <i h h 



Lead 7(v81 76-71) 76-05 76-82 



Sulphur 5-94 5-82 6-00 — 



Sodium — ()-15 0-15 — 



Behaviour of imidosulphonates as compound amines to other bodies. 



We collect together here some facts already recorded in the paper 

 which appear to show that imidosulphonates form compounds in 

 which the nitrogen becomes quinquevalent as in ammonium salts. 



First, in order of observation, there is the retention of one 

 molecule of water at 110° by the trisodium salt. The potassium salt 

 which crystallises with one molecule of water (Raschig) lias not been 

 examined in this regard. Next, there is the union of diammonium 

 salt with sodium nitrate to form a well-crystallised compound which 



