90 DIVERS AND HAGA. 



insoluble in water, and scarcely, if at all, alkaline in reaction when in 

 contact with wet litmus paper. 



A number of preparations by different methods have l^een 

 analysed with closely concordant results : — 



The lead acetate precipitates gave from 72-81 to 72'78 7o lead, 

 and from 7'52 to 7*65 7o «idphur. The sodium was determined in 

 some of these preparations, and was found to be no more than 

 0-075 7,. 



The pure salt was also titrated with volumetric nitric acid and 

 its basicity found to agree with calculation. One gramme of salt took 

 48-71 CCS. of acid, instead of 47*28 ces. calculated to just dissolve it 

 and furnish a solution neutral to methyl orange. 



Five-eight] I s-ox y -lead imidosulphonate, (R0Vl))^l^(K>i).).2, PbO or 

 Pb(0H)2. — This salt is precipitated on adding trisodium imidosul- 

 phonate to excess of basic lead acetate. The quantity of basic lead 

 acetate which is needed is very large. Trial taught us to use not 

 less than six molecules of hemi-hydroxy-lead acetate to one of tri- 

 sodium imidosulphonate. The calculated quantity is five molecules, 

 but an excess helps to keep sodium out of the salt. The reaction is as 

 follows : — 



NaeNlSOg)^ + öHOPbÜAc = (HOPb)3N(S03)2,Pb(OH)2 + SNaOAc + Pb(0Ä^)2 

 and therefore it would be better probably to use a more basic lead 

 acetate. Using as we did, about six molecules of hemi-hydroxy-lead 

 acetate, the mother-liquor of the precipitate proved to be markedly 

 basic still, l^oth precipitate and mother-liquor were quite free from 

 sulphate. A very little sodium, but no acetic acid, was found in the 

 precipitate, after it had been well -washed. It is readily soluble in 



