IMIDOSULPHOXATES. g 9 



evidently, hoth from its nppenraiife nnd nn imperfect analysis, the 

 hvdroxy-lead salt. 



The hydroxy-le:!d salt in perfect brilliant micr(3scopic prisms 

 can he obtained very pure by treating the more basic lead salt next 

 described, with little more nitric acid than that calculated to remove 

 tlie excess of lead. The nitric acid can be clearly seen to diss(:>lve a 

 [>ortion of more basic salt, and almost at once to deposit n crystalline 

 precipitate raid incrustation of the hemi-basic salt. If instead oi" 

 stopping the addition of nitric acid when enough has been used, more 

 is added, the crystalline salt proportionately dissolves without repre- 

 cipitating. The nitric solution is neutral to methyl orange, so that 

 the reaction is, in the dissolution of the more basic salt, — 



(HOPb)3NiÖÜ3)2, Pb(OH)2 + 6HN03-HPbN(S03)., + 50H2 + 3Pb(N03), 

 and then, this solution reacting with a further quantity of the more 

 basic sîdt : — 



2(HOPb)3N(S03)2, Pb(OH)2 + HPbN(S03)2-3(HOPb)3N(S03), + OH2 

 This, in a manner, can be shown by pouring, the nitric solution into 

 a large excess of hydr(3xy-lead acetate solution, when the hemi- 

 hydroxy-lead imidosulplionate also precipitates in the pure state. 

 There is also the f ict oljserved that the nitric liquor when soon poured 

 olf from undissolved more-basic salt contains much lead, whereas 

 when it is left over the undissolved more-basic salt it goes on deposit- 

 ing a crystaJline precipitate of the hemi-basic salt. 



The modification of this process expressed by the equation — 

 8(HüPb)3N(Ö03)2, Pb(OH)2-fHN(S03Na),-H'2HN03 = 4(HOPb),N(S03)2 



-—has also been quite successful, ]jy adding the nitiic acid very slowly 

 and shaking well. 



The hemi-liydroxy-lead iuiidosulplionate is an anhydrous salt, 

 not counting its hyclroxyl, very })ermanent, losing nothing at 100°, 



