bo 
TRANSACTIONS OF THE foo, <i; 
The first member of the series of fluoplumbates, derivatives of 
fluoplumbic acid, is the potassium salt described below; it has 
been obtained by the following methods: 
1. By treating the freshly precipitated oxide Pb,O,,3H,O 
which was first described by me in 1885 (Royal Society of 
Bohemia 295-299), as the intermediate compound between Pb,O, 
and Pb,O,, with hydrofluoric acid and potassium hydrogen 
fluoride. A mixture of lead fluoride and the crystalline fluo- 
plumbate is obtained, the latter being separated from the'former 
by recrystallization from hydrofluoric acid. : 
2. By substituting fluorine for oxygen in Fremy’s potassium 
plumbate, the crude salt containing potassium and lead dioxide 
in the proportion of 83K,0: PbO, is dissolved in hydrofluoric 
acid, and from the filtered liquid crystals separate out, which, if 
necessary, may be purified by recrystallization from hydrofluoric 
acid. Pa: ; 
3. By dissolving lead tetra-acetate Pb(C,H,0,), in hydroflu- 
oric acid containing acid potassium fluoride. On spontaneous 
evaporation of the solution, needle shaped crystals of the fluo- 
plumbate are obtained. 
The salt has the composition: 8K F.HF.PbF,, being tripotas- 
sium-monohydrogen orthofluoplumbate, as proved by the fol- 
lowing analytical data. 
Calculated for 
3K F.HF.PbF,. Found. 
iF > See ie Ve: 
3K 117-42 24°60 B4:bT ABS — 
Pb... :206°9 43°35 43.41 43°36 43°35 — — 
SE ccd 5220 31°84 — 31.23 — 381.65 — 
| egies 2 I 0:21 — — — — 0.22 
477°32 100-00 
The analysis shows that the substance contains no oxygen. 
The crystallographic examination of the salt was, in so far of 
theoretical interest,as Marignac has described a perfectly anal- 
ogous compound of quadrivalent tin, namely 3K F.HF.SnF,, for 
it shows that both salts are isomorphous. The crystals were 
examined by Prof. Ch. Vrba of our University, but unfortun- 
ately their faces are uneven and corroded, so that no absolutely 
exact crystallographic and optical examination could be made. 
Assuming the monoclinic symmetry as has been assumed by 
Marignac for the fluostannate, the elements are approximately : 
