Wells—Compounds containing Lead and extra Iodine. 21 
Art. Il.—On some Compounds containing Lead and extra 
Llodine; by H. L. WELLS. 
ABOUT two years ago the writer described* the double 
salts of lead tetrachloride, (NH,), PbCl,, K,PbCl,, Rb,PbCl, 
and Cs,PbCl,, and upon attempting to prepare the correspond- 
ing bromides and iodides, an entirely different kind of double 
salts was discovered.t These peculiar salts were K,Pb,Br,. 
4H,O and K,Pb,I,.4H,O. They are remarkable in containing 
but a single atom of extra halogen in the formula as given 
above, and they apparently correspond to no previously known 
compound. I was unable to obtain, with the alkali metals, 
any bromides or iodides corresponding to the chlorides, but it 
is interesting to notice that Classen and Zahorskit have 
obtained such salts with quinoline, (C,H,NH),PbBr, and 
RereL NEL, PbS. 
The isolation of lead tetrachloride by Friedrich| and the 
discovery of lead tetra-acetate, Pb(CH,CO,),, by Hutchinson 
and Pollard{| were very interesting additions to our knowledge 
of the compounds of tetravalent lead. These articles appeared 
almost simultaneously with that of Classen and Zahorski which 
_has been referred to above, and with my own work mentioned 
at the beginning of this article. 
As a sequence to my former investigations, it has seemed to 
be desirable to reinvestigate two previously described com- 
pounds containing lead and extra iodine, because it seemed 
possible that a further study of them might throw some light 
upon the nature of the curious salt, K,Pb,[,.4H,O. 
Johnson’s Salt.—By mixing a hot, concentrated alcoholic 
solution of potassium triiodide with a saturated solution of 
lead acetate in boiling alcohol, filtering off the small precipi- 
tate thus produced and cooling, G. 8. Johnson** obtained a 
erystalline substance to which he gave the formula, Pb,C,,H,, 
OL KI. Concerning this he remarks, “The formation of a 
rational formula has at present battled all my endeavors.” 
Johnson also obtained the salt by recrystallization from alco- 
_hol and by evaporating the mother-liquor over sulphuric acid, 
but there is no evidence that he analyzed more than one sam- 
ple of it. He does not give the quantities used in making his 
preparation. 
* This Journal, xlvi, 180, 1893. + This Journal, xlvi, 190, 1893. 
t Zeitschr. fur anorg. Chem., 4, 107, 1893. 
§ Classen and Zahorski gave a formula of different type, 5NH,Cl.2PbCl,, to 
the double ammonium chloride. It seems certain from analogy, from Friedrich’s 
results and from my own work, that their product was contaminated with 
ammonium chloride. || Berichte, 26, 1434, 1893. 
4 Chem. Soc. Jour., Ixiii, 1136, 1893. 
** Chem. Soc. Jour., xxxiii, 189, 1878. 
