Wells— Compounds containing Lead and extra Iodine. 23 
Lead and potassium were determined by dissolving the sub- 
stance in dilute nitric acid, evaporating with sulphuric acid, 
separating the lead sulphate by filtration, weighing it, and 
determining potassium in the filtrate by weighing it as sulphate. 
Iodine was determined by treating the substance with a solu- 
tion of sodium arsenite, acidifying with nitric acid and digest- 
ing with an excess of silver nitrate, and finally weighing silver 
iodide. Carbon and hydrogen were determined by combus- 
tion with lead chromate, where the front part of the tube con- 
tained a layer of metallic silver which stopped the passage of 
any iodine. 
The variations in the results of the analyses are considerable, 
and it is probable that the salt, being always deposited in a 
concentrated mother-liquor, was never quite pure, but there is 
no evidence that the variations in composition have been regu- 
larly influenced by the variations in the conditions of prepara- 
tion. The analyses are given in the order in which they were 
made. The last three probably represent better material than 
the others. 
Oxygen 
Lead. Potassium. Iodine. Carbon. Hydrogen. (difference.) 
I 30°51 4°01 37°50 ee wary wie 
iy 36°24 4°33 36°16 eas SNe Le 
Iil 35°83 4°52 36°01 tee di ae A bpe 
IV 30'29 4°07 37°78 a Pere feed Lathe 
V 36°21 4°59 ata ns ee et le 2 
VI 30°43 4°20 Bee) Meh AY NISL a7ie es 
VI 39°65 4°40 36°49 hea Sas a oss 
Vill 39°39 4°15 ayy Las SATE meee 
TX 34°80 4°42 Ly ap ss FPG e as eres 
xX 34°85 3°98 37°92 9°14 1°39 LD eT 
al 34°72 3°97 a0 2 6 SE, 14] 11°47 
AT 34°33 3°94 39°83 Sri 1°31 Lis2 
Calculated for 5Pb(CH,CO,),. 38KI. 6], 
a0°O7 4°07 39°62 8°31 1°04 11°09 
Johnson found, 
33°195 4°668 43°37 8°63 1°106 9°031 
It must be admitted that the results do not agree very satis- 
factorily with the calculated quantities, and that the formula is 
somewhat uncertain. It seems probable, however, that the 
compound is a combination of lead acetate with potassium 
triiodide with the formula 5Pb(CH,CO,),.3KI,. It is ‘not 
certain that the extra iodine is combined with the potassium 
rather than with the lead, but since KI, is a well-known com- 
pound, and since the acetic acid radical is present in the proper 
proportion to form lead acetate, this view seems to be the most 
plausible one. 
